Failsafe directory file system in a dispersed storage network

ABSTRACT

A file directory system comprises a directory file, a directory address for the directory file, and a directory address failsafe mechanism. The directory file includes one or more directory entries and one or more corresponding addresses for the one or more directory entries. The directory address failsafe mechanism functions to dispersed storage error encode the directory address to produce a plurality of encoded components of the directory address and transmit the plurality of encoded components of the directory address to a plurality of agent modules.

CROSS REFERENCE TO RELATED PATENTS

The present U.S. Utility Patent Application claims priority pursuant to35 U.S.C. §120 as a continuation of U.S. Utility Application No.13/021,657, entitled “FAILSAFE DIRECTORY FILE SYSTEM IN A DISPERSEDSTORAGE NETWORK”, filed 02/04/2011, issuing as U.S. Pat. No. 8,707,091on Apr. 22, 2014, which claims priority pursuant to 35 U.S.C. §119(e) toU.S. Provisional Application No. 61/313,885, entitled “DISTRIBUTEDSTORAGE SYSTEM ACCESS”, filed 03/15/2010, all of which are herebyincorporated herein by reference in their entirety and made part of thepresent U.S. Utility Patent Application for all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to computing systems and moreparticularly to data storage solutions within such computing systems.

2. Description of Related Art

Computers are known to communicate, process, and store data. Suchcomputers range from wireless smart phones to data centers that supportmillions of web searches, stock trades, or on-line purchases every day.In general, a computing system generates data and/or manipulates datafrom one form into another. For instance, an image sensor of thecomputing system generates raw picture data and, using an imagecompression program (e.g., JPEG, MPEG, etc.), the computing systemmanipulates the raw picture data into a standardized compressed image.

With continued advances in processing speed and communication speed,computers are capable of processing real time multimedia data forapplications ranging from simple voice communications to streaming highdefinition video. As such, general-purpose information appliances arereplacing purpose-built communications devices (e.g., a telephone). Forexample, smart phones can support telephony communications but they arealso capable of text messaging and accessing the internet to performfunctions including email, web browsing, remote applications access, andmedia communications (e.g., telephony voice, image transfer, musicfiles, video files, real time video streaming. etc.).

Each type of computer is constructed and operates in accordance with oneor more communication, processing, and storage standards. As a result ofstandardization and with advances in technology, more and moreinformation content is being converted into digital formats. Forexample, more digital cameras are now being sold than film cameras, thusproducing more digital pictures. As another example, web-basedprogramming is becoming an alternative to over the air televisionbroadcasts and/or cable broadcasts. As further examples, papers, books,video entertainment, home video, etc. are now being stored digitally,which increases the demand on the storage function of computers.

A typical computer storage system includes one or more memory devicesaligned with the needs of the various operational aspects of thecomputer's processing and communication functions. Generally, theimmediacy of access dictates what type of memory device is used. Forexample, random access memory (RAM) memory can be accessed in any randomorder with a constant response time, thus it is typically used for cachememory and main memory. By contrast, memory device technologies thatrequire physical movement such as magnetic disks, tapes, and opticaldiscs, have a variable response time as the physical movement can takelonger than the data transfer, thus they are typically used forsecondary memory (e.g., hard drive, backup memory, etc.).

A computer's storage system will be compliant with one or more computerstorage standards that include, but are not limited to, network filesystem (NFS), flash file system (FFS), disk file system (DFS), smallcomputer system interface (SCSI), internet small computer systeminterface (iSCSI), file transfer protocol (FTP), and web-baseddistributed authoring and versioning (WebDAV). These standards specifythe data storage format (e.g., files, data objects, data blocks,directories, etc.) and interfacing between the computer's processingfunction and its storage system, which is a primary function of thecomputer's memory controller.

Despite the standardization of the computer and its storage system,memory devices fail; especially commercial grade memory devices thatutilize technologies incorporating physical movement (e.g., a discdrive). For example, it is fairly common for a disc drive to routinelysuffer from bit level corruption and to completely fail after threeyears of use. One solution is to a higher-grade disc drive, which addssignificant cost to a computer.

Another solution is to utilize multiple levels of redundant disc drivesto replicate the data into two or more copies. One such redundant driveapproach is called redundant array of independent discs (RAID). In aRAID device, a RAID controller adds parity data to the original databefore storing it across the array. The parity data is calculated fromthe original data such that the failure of a disc will not result in theloss of the original data. For example, RAID 5 uses three discs toprotect data from the failure of a single disc. The parity data, andassociated redundancy overhead data, reduces the storage capacity ofthree independent discs by one third (e.g., n−1=capacity). RAID 6 canrecover from a loss of two discs and requires a minimum of four discswith a storage capacity of n−2.

While RAID addresses the memory device failure issue, it is not withoutits own failures issues that affect its effectiveness, efficiency andsecurity. For instance, as more discs are added to the array, theprobability of a disc failure increases, which increases the demand formaintenance. For example, when a disc fails, it needs to be manuallyreplaced before another disc fails and the data stored in the RAIDdevice is lost. To reduce the risk of data loss, data on a

RAID device is typically copied on to one or more other RAID devices.While this addresses the loss of data issue, it raises a security issuesince multiple copies of data are available, which increases the chancesof unauthorized access. Further, as the amount of data being storedgrows, the overhead of RAID devices becomes a non-trivial efficiencyissue.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic block diagram of an embodiment of a computingsystem in accordance with the invention;

FIG. 2 is a schematic block diagram of an embodiment of a computing corein accordance with the invention;

FIG. 3 is a schematic block diagram of an embodiment of a distributedstorage processing unit in accordance with the invention;

FIG. 4 is a schematic block diagram of an embodiment of a grid module inaccordance with the invention;

FIG. 5 is a diagram of an example embodiment of error coded data slicecreation in accordance with the invention;

FIG. 6 is a diagram of an example of a dispersed storage networkdirectory structure in accordance with the invention;

FIG. 7A is a diagram of another example of a dispersed storage networkdirectory structure in accordance with the invention;

FIG. 7B is a diagram of another example of a dispersed storage networkdirectory structure in accordance with the invention;

FIG. 8A is a diagram of another example of a dispersed storage networkdirectory structure in accordance with the invention;

FIG. 8B is a diagram of another example of a dispersed storage networkdirectory structure in accordance with the invention;

FIG. 8C is a diagram of another example of a dispersed storage networkdirectory structure in accordance with the invention;

FIG. 8D is a diagram of another example of a dispersed storage networkdirectory structure in accordance with the invention;

FIG. 9A is a flowchart illustrating an example of accessing directoryinformation in accordance with the invention;

FIG. 9B is a flowchart illustrating an example of retrieving directoryinformation in accordance with the invention;

FIG. 10 is a diagram illustrating an example of manager informationstructure in accordance with the invention;

FIG. 11 is a flowchart illustrating an example of storing managerinformation in accordance with the invention;

FIG. 12 is a flowchart illustrating an example of storing a manager hostkey in accordance with the invention;

FIG. 13 is a flowchart illustrating an example of retrieving a managerhost key in accordance with the invention;

FIG. 14 is a flowchart illustrating an example of associating accesscontrol information with an encoded data slice in accordance with theinvention;

FIG. 15 is a flowchart illustrating an example of authenticating anencoded data slice access request in accordance with the invention;

FIG. 16 is a flowchart illustrating an example of modifying a deliveredservice level in accordance with the invention;

FIG. 17A is a schematic block diagram of another embodiment of acomputing system in accordance with the invention;

FIG. 17B is a diagram of a reliability pulldown menu in accordance withthe invention;

FIG. 18 is a flowchart illustrating an example of generating a storedata object request in accordance with the invention; and

FIG. 19 is a flowchart illustrating an example of generating a storedata object response in accordance with invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic block diagram of a computing system 10 thatincludes one or more of a first type of user devices 12, one or more ofa second type of user devices 14, at least one distributed storage (DS)processing unit 16, at least one DS managing unit 18, at least onestorage integrity processing unit 20, and a distributed storage network(DSN) memory 22 coupled via a network 24. The network 24 may include oneor more wireless and/or wire lined communication systems; one or moreprivate intranet systems and/or public internet systems; and/or one ormore local area networks (LAN) and/or wide area networks (WAN).

The DSN memory 22 includes a plurality of distributed storage (DS) units36 for storing data of the system. Each of the DS units 36 includes aprocessing module and memory and may be located at a geographicallydifferent site than the other DS units (e.g., one in Chicago, one inMilwaukee, etc.). The processing module may be a single processingdevice or a plurality of processing devices. Such a processing devicemay be a microprocessor, micro-controller, digital signal processor,microcomputer, central processing unit, field programmable gate array,programmable logic device, state machine, logic circuitry, analogcircuitry, digital circuitry, and/or any device that manipulates signals(analog and/or digital) based on hard coding of the circuitry and/oroperational instructions. The processing module may have an associatedmemory and/or memory element, which may be a single memory device, aplurality of memory devices, and/or embedded circuitry of the processingmodule. Such a memory device may be a read-only memory, random accessmemory, volatile memory, non-volatile memory, static memory, dynamicmemory, flash memory, cache memory, and/or any device that storesdigital information. Note that if the processing module includes morethan one processing device, the processing devices may be centrallylocated (e.g., directly coupled together via a wired and/or wireless busstructure) or may be distributedly located (e.g., cloud computing viaindirect coupling via a local area network and/or a wide area network).Further note that when the processing module implements one or more ofits functions via a state machine, analog circuitry, digital circuitry,and/or logic circuitry, the memory and/or memory element storing thecorresponding operational instructions may be embedded within, orexternal to, the circuitry comprising the state machine, analogcircuitry, digital circuitry, and/or logic circuitry. Still further notethat, the memory element stores, and the processing module executes,hard coded and/or operational instructions corresponding to at leastsome of the steps and/or functions illustrated in FIGS. 1-19.

Each of the user devices 12-14, the DS processing unit 16, the DSmanaging unit 18, and the storage integrity processing unit 20 may be aportable computing device (e.g., a social networking device, a gamingdevice, a cell phone, a smart phone, a personal digital assistant, adigital music player, a digital video player, a laptop computer, ahandheld computer, a video game controller, and/or any other portabledevice that includes a computing core) and/or a fixed computing device(e.g., a personal computer, a computer server, a cable set-top box, asatellite receiver, a television set, a printer, a fax machine, homeentertainment equipment, a video game console, and/or any type of homeor office computing equipment). Such a portable or fixed computingdevice includes a computing core 26 and one or more interfaces 30, 32,and/or 33. An embodiment of the computing core 26 will be described withreference to FIG. 2.

With respect to the interfaces, each of the interfaces 30, 32, and 33includes software and/or hardware to support one or more communicationlinks via the network 24 and/or directly. For example, interfaces 30support a communication link (wired, wireless, direct, via a LAN, viathe network 24, etc.) between the first type of user device 14 and theDS processing unit 16. As another example, DSN interface 32 supports aplurality of communication links via the network 24 between the DSNmemory 22 and the DS processing unit 16, the first type of user device12, and/or the storage integrity processing unit 20. As yet anotherexample, interface 33 supports a communication link between the DSmanaging unit 18 and any one of the other devices and/or units 12, 14,16, 20, and/or 22 via the network 24.

In general and with respect to data storage, the system 10 supportsthree primary functions: distributed network data storage management,distributed data storage and retrieval, and data storage integrityverification. In accordance with these three primary functions, data canbe distributedly stored in a plurality of physically different locationsand subsequently retrieved in a reliable and secure manner regardless offailures of individual storage devices, failures of network equipment,the duration of storage, the amount of data being stored, attempts athacking the data, etc.

The DS managing unit 18 performs distributed network data storagemanagement functions, which include establishing distributed datastorage parameters, performing network operations, performing networkadministration, and/or performing network maintenance. The DS managingunit 18 establishes the distributed data storage parameters (e.g.,allocation of virtual DSN memory space, distributed storage parameters,security parameters, billing information, user profile information,etc.) for one or more of the user devices 12-14 (e.g., established forindividual devices, established for a user group of devices, establishedfor public access by the user devices, etc.). For example, the DSmanaging unit 18 coordinates the creation of a vault (e.g., a virtualmemory block) within the DSN memory 22 for a user device (for a group ofdevices, or for public access). The DS managing unit 18 also determinesthe distributed data storage parameters for the vault. In particular,the DS managing unit 18 determines a number of slices (e.g., the numberthat a data segment of a data file and/or data block is partitioned intofor distributed storage) and a read threshold value (e.g., the minimumnumber of slices required to reconstruct the data segment).

As another example, the DS managing module 18 creates and stores,locally or within the DSN memory 22, user profile information. The userprofile information includes one or more of authentication information,permissions, and/or the security parameters. The security parameters mayinclude one or more of encryption/decryption scheme, one or moreencryption keys, key generation scheme, and data encoding/decodingscheme.

As yet another example, the DS managing unit 18 creates billinginformation for a particular user, user group, vault access, publicvault access, etc. For instance, the DS managing unit 18 tracks thenumber of times user accesses a private vault and/or public vaults,which can be used to generate a per-access bill. In another instance,the DS managing unit 18 tracks the amount of data stored and/orretrieved by a user device and/or a user group, which can be used togenerate a per-data-amount bill.

The DS managing unit 18 also performs network operations, networkadministration, and/or network maintenance. As at least part ofperforming the network operations and/or administration, the DS managingunit 18 monitors performance of the devices and/or units of the system10 for potential failures, determines the devices and/or unit'sactivation status, determines the devices' and/or units' loading, andany other system level operation that affects the performance level ofthe system 10. For example, the DS managing unit 18 receives andaggregates network management alarms, alerts, errors, statusinformation, performance information, and messages from the devices12-14 and/or the units 16, 20, 22. For example, the DS managing unit 18receives a simple network management protocol (SNMP) message regardingthe status of the DS processing unit 16.

The DS managing unit 18 performs the network maintenance by identifyingequipment within the system 10 that needs replacing, upgrading,repairing, and/or expanding. For example, the DS managing unit 18determines that the DSN memory 22 needs more DS units 36 or that one ormore of the DS units 36 needs updating.

The second primary function (i.e., distributed data storage andretrieval) begins and ends with a user device 12-14. For instance, if asecond type of user device 14 has a data file 38 and/or data block 40 tostore in the DSN memory 22, it send the data file 38 and/or data block40 to the DS processing unit 16 via its interface 30. As will bedescribed in greater detail with reference to FIG. 2, the interface 30functions to mimic a conventional operating system (OS) file systeminterface (e.g., network file system (NFS), flash file system (FFS),disk file system (DFS), file transfer protocol (FTP), web-baseddistributed authoring and versioning (WebDAV), etc.) and/or a blockmemory interface (e.g., small computer system interface (SCSI), internetsmall computer system interface (iSCSI), etc.). In addition, theinterface 30 may attach a user identification code (ID) to the data file38 and/or data block 40.

The DS processing unit 16 receives the data file 38 and/or data block 40via its interface 30 and performs a distributed storage (DS) process 34thereon (e.g., an error coding dispersal storage function). The DSprocessing 34 begins by partitioning the data file 38 and/or data block40 into one or more data segments, which is represented as Y datasegments. For example, the DS processing 34 may partition the data file38 and/or data block 40 into a fixed byte size segment (e.g., 2 ¹ to 2^(n) bytes, where n=>2) or a variable byte size (e.g., change byte sizefrom segment to segment, or from groups of segments to groups ofsegments, etc.).

For each of the Y data segments, the DS processing 34 error encodes(e.g., forward error correction (FEC), information dispersal algorithm,or error correction coding) and slices (or slices then error encodes)the data segment into a plurality of error coded (EC) data slices 42-48,which is represented as X slices per data segment. The number of slices(X) per segment, which corresponds to a number of pillars n, is set inaccordance with the distributed data storage parameters and the errorcoding scheme. For example, if a Reed-Solomon (or other FEC scheme) isused in an n/k system, then a data segment is divided into n slices,where k number of slices is needed to reconstruct the original data(i.e., k is the threshold). As a few specific examples, the n/k factormay be 5/3; 6/4; 8/6; 8/5; 16/10.

For each slice 42-48, the DS processing unit 16 creates a unique slicename and appends it to the corresponding slice 42-48. The slice nameincludes universal DSN memory addressing routing information (e.g.,virtual memory addresses in the DSN memory 22) and user-specificinformation (e.g., user ID, file name, data block identifier, etc.).

The DS processing unit 16 transmits the plurality of EC slices 42-48 toa plurality of DS units 36 of the DSN memory 22 via the DSN interface 32and the network 24. The DSN interface 32 formats each of the slices fortransmission via the network 24. For example, the DSN interface 32 mayutilize an internet protocol (e.g., TCP/IP, etc.) to packetize theslices 42-48 for transmission via the network 24.

The number of DS units 36 receiving the slices 42-48 is dependent on thedistributed data storage parameters established by the DS managing unit18. For example, the DS managing unit 18 may indicate that each slice isto be stored in a different DS unit 36. As another example, the DSmanaging unit 18 may indicate that like slice numbers of different datasegments are to be stored in the same DS unit 36. For example, the firstslice of each of the data segments is to be stored in a first DS unit36, the second slice of each of the data segments is to be stored in asecond DS unit 36, etc. In this manner, the data is encoded anddistributedly stored at physically diverse locations to improved datastorage integrity and security. Further examples of encoding the datasegments will be provided with reference to one or more of FIGS. 2-19.

Each DS unit 36 that receives a slice 42-48 for storage translates thevirtual DSN memory address of the slice into a local physical addressfor storage. Accordingly, each DS unit 36 maintains a virtual tophysical memory mapping to assist in the storage and retrieval of data.

The first type of user device 12 performs a similar function to storedata in the DSN memory 22 with the exception that it includes the DSprocessing. As such, the device 12 encodes and slices the data fileand/or data block it has to store. The device then transmits the slices11 to the DSN memory via its DSN interface 32 and the network 24.

For a second type of user device 14 to retrieve a data file or datablock from memory, it issues a read command via its interface 30 to theDS processing unit 16. The DS processing unit 16 performs the DSprocessing 34 to identify the DS units 36 storing the slices of the datafile and/or data block based on the read command. The DS processing unit16 may also communicate with the DS managing unit 18 to verify that theuser device 14 is authorized to access the requested data.

Assuming that the user device is authorized to access the requesteddata, the DS processing unit 16 issues slice read commands to at least athreshold number of the DS units 36 storing the requested data (e.g., toat least 10 DS units for a 16/10 error coding scheme). Each of the DSunits 36 receiving the slice read command, verifies the command,accesses its virtual to physical memory mapping, retrieves the requestedslice, or slices, and transmits it to the DS processing unit 16.

Once the DS processing unit 16 has received a read threshold number ofslices for a data segment, it performs an error decoding function andde-slicing to reconstruct the data segment. When Y number of datasegments has been reconstructed, the DS processing unit 16 provides thedata file 38 and/or data block 40 to the user device 14. Note that thefirst type of user device 12 performs a similar process to retrieve adata file and/or data block.

The storage integrity processing unit 20 performs the third primaryfunction of data storage integrity verification. In general, the storageintegrity processing unit 20 periodically retrieves slices 45, and/orslice names, of a data file or data block of a user device to verifythat one or more slices have not been corrupted or lost (e.g., the DSunit failed). The retrieval process mimics the read process previouslydescribed.

If the storage integrity processing unit 20 determines that one or moreslices is corrupted or lost, it rebuilds the corrupted or lost slice(s)in accordance with the error coding scheme. The storage integrityprocessing unit 20 stores the rebuild slice, or slices, in theappropriate DS unit(s) 36 in a manner that mimics the write processpreviously described.

FIG. 2 is a schematic block diagram of an embodiment of a computing core26 that includes a processing module 50, a memory controller 52, mainmemory 54, a video graphics processing unit 55, an input/output (IO)controller 56, a peripheral component interconnect (PCI) interface 58,at least one IO device interface module 62, a read only memory (ROM)basic input output system (BIOS) 64, and one or more memory interfacemodules. The memory interface module(s) includes one or more of auniversal serial bus (USB) interface module 66, a host bus adapter (HBA)interface module 68, a network interface module 70, a flash interfacemodule 72, a hard drive interface module 74, and a DSN interface module76. Note the DSN interface module 76 and/or the network interface module70 may function as the interface 30 of the user device 14 of FIG. 1.Further note that the 10 device interface module 62 and/or the memoryinterface modules may be collectively or individually referred to as 10ports.

The processing module 50 may be a single processing device or aplurality of processing devices. Such a processing device may be amicroprocessor, micro-controller, digital signal processor,microcomputer, central processing unit, field programmable gate array,programmable logic device, state machine, logic circuitry, analogcircuitry, digital circuitry, and/or any device that manipulates signals(analog and/or digital) based on hard coding of the circuitry and/oroperational instructions. The processing module 50 may have anassociated memory and/or memory element, which may be a single memorydevice, a plurality of memory devices, and/or embedded circuitry of theprocessing module 50. Such a memory device may be a read-only memory,random access memory, volatile memory, non-volatile memory, staticmemory, dynamic memory, flash memory, cache memory, and/or any devicethat stores digital information. Note that if the processing module 50includes more than one processing device, the processing devices may becentrally located (e.g., directly coupled together via a wired and/orwireless bus structure) or may be distributedly located (e.g., cloudcomputing via indirect coupling via a local area network and/or a widearea network). Further note that when the processing module 50implements one or more of its functions via a state machine, analogcircuitry, digital circuitry, and/or logic circuitry, the memory and/ormemory element storing the corresponding operational instructions may beembedded within, or external to, the circuitry comprising the statemachine, analog circuitry, digital circuitry, and/or logic circuitry.Still further note that, the memory element stores, and the processingmodule 50 executes, hard coded and/or operational instructionscorresponding to at least some of the steps and/or functions illustratedin FIGS. 1-19.

FIG. 3 is a schematic block diagram of an embodiment of a dispersedstorage (DS) processing module 34 of user device 12 and/or of the DSprocessing unit 16. The DS processing module 34 includes a gatewaymodule 78, an access module 80, a grid module 82, and a storage module84. The DS processing module 34 may also include an interface 30 and theDSnet interface 32 or the interfaces 68 and/or 70 may be part of user 12or of the DS processing unit 14. The DS processing module 34 may furtherinclude a bypass/feedback path between the storage module 84 to thegateway module 78. Note that the modules 78-84 of the DS processingmodule 34 may be in a single unit or distributed across multiple units.

In an example of storing data, the gateway module 78 receives anincoming data object that includes a user ID field 86, an object namefield 88, and the data field 40 and may also receive correspondinginformation that includes a process identifier (e.g., an internalprocess/application ID), metadata, a file system directory, a blocknumber, a transaction message, a user device identity (ID), a dataobject identifier, a source name, and/or user information. The gatewaymodule 78 authenticates the user associated with the data object byverifying the user ID 86 with the managing unit 18 and/or anotherauthenticating unit.

When the user is authenticated, the gateway module 78 obtains userinformation from the management unit 18, the user device, and/or theother authenticating unit. The user information includes a vaultidentifier, operational parameters, and user attributes (e.g., userdata, billing information, etc.). A vault identifier identifies a vault,which is a virtual memory space that maps to a set of DS storage units36. For example, vault 1 (i.e., user 1's DSN memory space) includeseight DS storage units (X=8 wide) and vault 2 (i.e., user 2's DSN memoryspace) includes sixteen DS storage units (X=16 wide). The operationalparameters may include an error coding algorithm, the width n (number ofpillars X or slices per segment for this vault), a read threshold T, awrite threshold, an encryption algorithm, a slicing parameter, acompression algorithm, an integrity check method, caching settings,parallelism settings, and/or other parameters that may be used to accessthe DSN memory layer.

The gateway module 78 uses the user information to assign a source name35 to the data. For instance, the gateway module 60 determines thesource name 35 of the data object 40 based on the vault identifier andthe data object. For example, the source name may contain a fileidentifier (ID), a vault generation number, a reserved field, and avault identifier (ID). As another example, the gateway module 78 maygenerate the file ID based on a hash function of the data object 40.Note that the gateway module 78 may also perform message conversion,protocol conversion, electrical conversion, optical conversion, accesscontrol, user identification, user information retrieval, trafficmonitoring, statistics generation, configuration, management, and/orsource name determination.

The access module 80 receives the data object 40 and creates a series ofdata segments 1 through Y 90-92 in accordance with a data storageprotocol (e.g., file storage system, a block storage system, and/or anaggregated block storage system). The number of segments Y may be chosenor randomly assigned based on a selected segment size and the size ofthe data object. For example, if the number of segments is chosen to bea fixed number, then the size of the segments varies as a function ofthe size of the data object. For instance, if the data object is animage file of 4,194,304 eight bit bytes (e.g., 33,554,432 bits) and thenumber of segments Y=131,072, then each segment is 256 bits or 32 bytes.As another example, if segment sized is fixed, then the number ofsegments Y varies based on the size of data object. For instance, if thedata object is an image file of 4,194,304 bytes and the fixed size ofeach segment is 4,096 bytes, the then number of segments Y=1,024. Notethat each segment is associated with the same source name.

The grid module 82 receives the data segments and may manipulate (e.g.,compression, encryption, cyclic redundancy check (CRC), etc.) each ofthe data segments before performing an error coding function of theerror coding dispersal storage function to produce a pre-manipulateddata segment. After manipulating a data segment, if applicable, the gridmodule 82 error encodes (e.g., Reed-Solomon, Convolution encoding,Trellis encoding, etc.) the data segment or manipulated data segmentinto X error coded data slices 42-44.

The value X, or the number of pillars (e.g., X=16), is chosen as aparameter of the error coding dispersal storage function. Otherparameters of the error coding dispersal function include a readthreshold T, a write threshold W, etc. The read threshold (e.g., T=10,when X=16 corresponds to the minimum number of error-free error codeddata slices required to reconstruct the data segment. In other words,the DS processing module 34 can compensate for X-T (e.g., 16-10=6)missing error coded data slices per data segment. The write threshold Wcorresponds to a minimum number of DS storage units that acknowledgeproper storage of their respective data slices before the DS processingmodule indicates proper storage of the encoded data segment. Note thatthe write threshold is greater than or equal to the read threshold for agiven number of pillars (X).

For each data slice of a data segment, the grid module 82 generates aunique slice name 37 and attaches it thereto. The slice name 37 includesa universal routing information field and a vault specific field and maybe 48 bytes (e.g., 24 bytes for each of the universal routinginformation field and the vault specific field). As illustrated, theuniversal routing information field includes a slice index, a vault ID,a vault generation, and a reserved field. The slice index is based onthe pillar number and the vault ID and, as such, is unique for eachpillar (e.g., slices of the same pillar for the same vault for anysegment will share the same slice index). The vault specific fieldincludes a data name, which includes a file ID and a segment number(e.g., a sequential numbering of data segments 1-Y of a simple dataobject or a data block number).

Prior to outputting the error coded data slices of a data segment, thegrid module may perform post-slice manipulation on the slices. Ifenabled, the manipulation includes slice level compression, encryption,CRC, addressing, tagging, and/or other manipulation to improve theeffectiveness of the computing system.

When the error coded data slices of a data segment are ready to beoutputted, the grid module 82 determines which of the DS storage units36 will store the EC data slices based on a dispersed storage memorymapping associated with the user's vault and/or DS storage unitattributes. The DS storage unit attributes may include availability,self-selection, performance history, link speed, link latency,ownership, available DSN memory, domain, cost, a prioritization scheme,a centralized selection message from another source, a lookup table,data ownership, and/or any other factor to optimize the operation of thecomputing system. Note that the number of DS storage units 36 is equalto or greater than the number of pillars (e.g., X) so that no more thanone error coded data slice of the same data segment is stored on thesame DS storage unit 36. Further note that EC data slices of the samepillar number but of different segments (e.g., EC data slice 1 of datasegment 1 and EC data slice 1 of data segment 2) may be stored on thesame or different DS storage units 36.

The storage module 84 performs an integrity check on the outboundencoded data slices and, when successful, identifies a plurality of DSstorage units based on information provided by the grid module 82. Thestorage module 84 then outputs the encoded data slices 1 through X ofeach segment 1 through Y to the DS storage units 36. Each of the DSstorage units 36 stores its EC data slice(s) and maintains a localvirtual DSN address to physical location table to convert the virtualDSN address of the EC data slice(s) into physical storage addresses.

In an example of a read operation, the user device 12 and/or 14 sends aread request to the DS processing unit 14, which authenticates therequest. When the request is authentic, the DS processing unit 14 sendsa read message to each of the DS storage units 36 storing slices of thedata object being read. The slices are received via the DSnet interface32 and processed by the storage module 84, which performs a parity checkand provides the slices to the grid module 82 when the parity check wassuccessful. The grid module 82 decodes the slices in accordance with theerror coding dispersal storage function to reconstruct the data segment.The access module 80 reconstructs the data object from the data segmentsand the gateway module 78 formats the data object for transmission tothe user device.

FIG. 4 is a schematic block diagram of an embodiment of a grid module 82that includes a control unit 73, a pre-slice manipulator 75, an encoder77, a slicer 79, a post-slice manipulator 81, a pre-slice de-manipulator83, a decoder 85, a de-slicer 87, and/or a post-slice de-manipulator 89.Note that the control unit 73 may be partially or completely external tothe grid module 82. For example, the control unit 73 may be part of thecomputing core at a remote location, part of a user device, part of theDS managing unit 18, or distributed amongst one or more DS storageunits.

In an example of write operation, the pre-slice manipulator 75 receivesa data segment 90-92 and a write instruction from an authorized userdevice. The pre-slice manipulator 75 determines if pre-manipulation ofthe data segment 90-92 is required and, if so, what type. The pre-slicemanipulator 75 may make the determination independently or based oninstructions from the control unit 73, where the determination is basedon a computing system-wide predetermination, a table lookup, vaultparameters associated with the user identification, the type of data,security requirements, available DSN memory, performance requirements,and/or other metadata.

Once a positive determination is made, the pre-slice manipulator 75manipulates the data segment 90-92 in accordance with the type ofmanipulation. For example, the type of manipulation may be compression(e.g., Lempel-Ziv-Welch, Huffman, Golomb, fractal, wavelet, etc.),signatures (e.g., Digital Signature Algorithm (DSA), Elliptic Curve DSA,Secure Hash Algorithm, etc.), watermarking, tagging, encryption (e.g.,Data Encryption Standard, Advanced Encryption Standard, etc.), addingmetadata (e.g., time/date stamping, user information, file type, etc.),cyclic redundancy check (e.g., CRC32), and/or other data manipulationsto produce the pre-manipulated data segment.

The encoder 77 encodes the pre-manipulated data segment 92 using aforward error correction (FEC) encoder (and/or other type of erasurecoding and/or error coding) to produce an encoded data segment 94. Theencoder 77 determines which forward error correction algorithm to usebased on a predetermination associated with the user's vault, a timebased algorithm, user direction, DS managing unit direction, controlunit direction, as a function of the data type, as a function of thedata segment 92 metadata, and/or any other factor to determine algorithmtype. The forward error correction algorithm may be Golay,Multidimensional parity, Reed-Solomon, Hamming, Bose Ray ChauduriHocquenghem (BCH), Cauchy-Reed-Solomon, or any other FEC encoder. Notethat the encoder 77 may use a different encoding algorithm for each datasegment 92, the same encoding algorithm for the data segments 92 of adata object, or a combination thereof.

The encoded data segment 94 is of greater size than the data segment 92by the overhead rate of the encoding algorithm by a factor of X/T, whereX is the width or number of slices, and T is the read threshold. In thisregard, the corresponding decoding process can accommodate at most X-Tmissing EC data slices and still recreate the data segment 92. Forexample, if X=16 and T=10, then the data segment 92 will be recoverableas long as 10 or more EC data slices per segment are not corrupted.

The slicer 79 transforms the encoded data segment 94 into EC data slicesin accordance with the slicing parameter from the vault for this userand/or data segment 92. For example, if the slicing parameter is X=16,then the slicer 79 slices each encoded data segment 94 into 16 encodedslices.

The post-slice manipulator 81 performs, if enabled, post-manipulation onthe encoded slices to produce the EC data slices. If enabled, thepost-slice manipulator 81 determines the type of post-manipulation,which may be based on a computing system-wide predetermination,parameters in the vault for this user, a table lookup, the useridentification, the type of data, security requirements, available DSNmemory, performance requirements, control unit directed, and/or othermetadata. Note that the type of post-slice manipulation may includeslice level compression, signatures, encryption, CRC, addressing,watermarking, tagging, adding metadata, and/or other manipulation toimprove the effectiveness of the computing system.

In an example of a read operation, the post-slice de-manipulator 89receives at least a read threshold number of EC data slices and performsthe inverse function of the post-slice manipulator 81 to produce aplurality of encoded slices. The de-slicer 87 de-slices the encodedslices to produce an encoded data segment 94. The decoder 85 performsthe inverse function of the encoder 77 to recapture the data segment90-92. The pre-slice de-manipulator 83 performs the inverse function ofthe pre-slice manipulator 75 to recapture the data segment 90-92.

FIG. 5 is a diagram of an example of slicing an encoded data segment 94by the slicer 79. In this example, the encoded data segment 94 includesthirty-two bits, but may include more or less bits. The slicer 79disperses the bits of the encoded data segment 94 across the EC dataslices in a pattern as shown. As such, each EC data slice does notinclude consecutive bits of the data segment 94 reducing the impact ofconsecutive bit failures on data recovery. For example, if EC data slice2 (which includes bits 1, 5, 9, 13, 17, 25, and 29) is unavailable(e.g., lost, inaccessible, or corrupted), the data segment can bereconstructed from the other EC data slices (e.g., 1, 3 and 4 for a readthreshold of 3 and a width of 4).

FIG. 6 is a diagram of an example of a dispersed storage network (DSN)directory structure that includes a plurality of directory files 102-106linking to encoded data slices files 112. Such a directory structure maybe utilized to determine a DSN address where encoded data slices arestored that correspond to a particular data object name. Note that theplurality of directory files 102-106 structure includes chaining suchthat a parent directory file points to a plurality of children recordfiles and so on through any number of layers such that a DSN address(e.g., source name) contained in the last layer may be utilized toaccess corresponding encoded data slices of a desired data object name.For example, a set of chained directory files represents a directorystructure for one user vault. As another example, a set of chaineddirectory files represents a directory structure for two or more uservaults. Note that a first directory file (e.g., a root directory file)may be addressed at a predetermined DSN address (e.g., a root addresssuch as address 0000) and subsequent children directory files are linkedback to the first directory file. Further note that the plurality ofdirectory files 102-106 is stored in memory to be subsequently retrievedwhen it is desired to access one or more data files referenced by thedirectory structure. For example, the plurality of directory files102-106 is stored as encoded directory slices in a DSN memory.

The directory files 102-106 include one or more directory entries 116,124, 132, one or more corresponding addresses 120, 128, 136 for the oneor more directory entries 116, 124, 132, and a size field 118, 126, 134;where the directory entries 116, 124, 132 include at least one of adirectory pathname and a file name. As such, directory entries 116, 124,132, may depict a directory path to a corresponding layer of thedirectory structure or a file name that is stored at a DSN address ofthe DSN address field 120, 128, 136. Note that the directory file mayinclude a flag to signify that the file or directory name field containsa filename or a directory name. The size field 118, 126, 134 representsthe number of bytes contained in the subsequent directory files andencoded directory slice files at layers below a current layer. The oneor more corresponding addresses 120, 128, 136 may be utilized to depicta DSN address (e.g., a source name) of a child layer that is at a nextlayer down in the directory structure. Each of the directory files102-106 is associated with a directory address 114, 122, and 130. Forexample, the directory addresses 114, 122, 130 include a DSN address ofwhere slices are stored associated with the corresponding directoryfile. Note that the directory address 114 constitutes a root directoryaddress (e.g., =0) when the directory file constitutes a root directoryfile 102.

In an example, directory file 104 is stored at DSN address 10 andcontains three entries. The first entry has a file or directory namefield 124 value of /user/charts to signify that the pathname at thislayer is /user/charts, a size field value of S5 (e.g., 4 gigabytes), anda DSN address of address 11 (e.g., the source of the next layer alongthat pathname). The second entry has a file or directory name fieldvalue of /user/temp to signify that the pathname at this layer is/user/temp, a size field value of S6, and a DSN address of address 15.The third entry has a file or directory name field value of /user/docsto signify that the pathname at this layer is /user/docs, a size fieldvalue of S7, and a DSN address of address 17.

Note that the /user pathname of the first directory file (e.g., rootdirectory file 102) points to a second (e.g., intermediate) directoryfile (e.g., directory file 104 at DSN address 10). The/user/temppathname of the second directory file points to a third directory file106 at DSN address 15. The /user/temp/picture.jpg file name of the thirddirectory file points to DSN address 78 where encoded data slices arestored for this data object name. The DSN address 78 (e.g., the sourcename) is utilized to determine slice names where the encoded data slicesare stored utilizing the source name to slice names 108 processpreviously described. The slice names are utilized to look up dispersedstorage (DS) unit locations (e.g., in the virtual DSN address tophysical location table) in a DS unit locations look up process 110 aspreviously discussed to determine where the encoded data slices arestored in the DSN memory.

The encoded data slice files 112 include a slice name field 140, asource name field 142, a file or directory name field 144, and encodeddata slices 146 and may further include one or more of a checksum field,a metadata field, a data size field, the user identifier (ID) field, anda vault ID. In an example, the encoded data slice files 112 areorganized in a four pillar wide system. The slice name field 140includes slice names 1_1, 1_2, 1_3, and 1_4. The source name field 142includes DSN address 78. The file or directory name field 144 includesthe filename /user/temp/picture.jpg. The encoded data slices pillarfield 146 includes pillar-slices addresses for each of the four pillars,which, in this example, corresponds to one of Y data segments. Theencoded data slice files are stored in the memory of the DS unit aspreviously discussed.

In a data retrieval example of operation, a processing module determinesa root directory dispersed storage network (DSN) address based on a uservault lookup for a requested data ID. Note that the data ID may includeat least one of a filename, a directory name, a path, and a blocknumber. Next, the processing module retrieves a set of encoded rootdirectory slices from a DSN memory based on the root directory DSNaddress. The processing module dispersed storage error decodes the setof encoded root directory slices to reproduce a root directory, whichincludes at least one of a filename, a path, a size indicator, and a DSNaddress. The processing module utilizes the DSN address to link toeither a file stored as slices in a DSN memory or to a directory filethat is stored as slices in the DSN memory. Note that there may be anynumber of linked intermediate directory files between the root directoryand a directory file containing the DSN address of a desired filename.The processing module determines if the root directory includes a DSNaddress that links to another record file or to a desired file based onwhether any of the entries of the directory include a desired filenameof the desired file. The processing module extracts a data DSN addressfrom the root directory when the filename is stored in the rootdirectory.

The processing module enters into a processing sequence when thefilename corresponding to a desired data ID is not stored in the rootdirectory. In such a processing sequence, the processing module beginsthe sequence by extracting a current intermediate directory DSN addressfrom a preceding directory (e.g., the root directory during a firstportion of the sequence); where the current intermediate directory DSNaddress includes at least one source name and at least one slice name.Next, the processing module retrieves a set of encoded currentintermediate directory slices from the DSN memory based on the currentintermediate directory DSN address. The method of the sequence continueswhere the processing module dispersed storage error encodes the set ofencoded current intermediate directory slices to reproduce a currentintermediate directory.

Next, the processing module determines whether the filename is stored inthe current intermediate directory. The processing module repeats theprocessing sequence for a next current intermediate directory DSNaddress when the filename is not stored in the current intermediatedirectory. The processing module extracts a data DSN address and exitsthe processing sequence when the filename is stored in the currentintermediate directory. In the retrieval example of operation continued,the processing module retrieves a set of encoded data slices from theDSN memory based on a data DSN address subsequent to the processingsequence. Next, the processing module dispersed storage error encodesthe set of encoded data slices to reproduce data.

In a data storage example of operation, a method begins where aprocessing module receives a data storage request, which may includedata and a data identifier (ID). Next, the processing module dispersedstorage error encodes the data to produce a set of encoded data slices.The method continues with the processing module determining a datadispersed storage network (DSN) address based on the data ID. Such adata DSN address may include at least one of a source name and at leastone slice name. The method continues with the processing module sendingthe set of encoded data slices to a DSN memory for storage at the dataDSN address. The method continues with the processing module updating adirectory file with path information corresponding to the data ID andthe data DSN address to produce an updated directory file. Note that thedirectory file may include one or more directories, wherein a directoryof the one or more directories includes at least one of a filename, apath, a size indicator, and a DSN address.

When updating the directory file, the processing module determineswhether the directory file is stored in the DSN memory, retrieves a setof encoded directory slices from the DSN memory based on the directoryDSN address, and dispersed storage error decodes the set of encodeddirectory slices to reproduce the directory file when the processingmodule determines that the directory file is stored in the DSN memory.The processing module creates the directory file to include at least oneof a filename field, a path field, a size indicator field, and a DSNaddress field when the directory file is not stored in the DSN memory.Alternatively, or in addition to, the processing module may update thedirectory file by obtaining a parent directory (e.g., another higherlevel intermediate directory or the root directory), updating the parentdirectory with the directory DSN address and at least a portion of thedata ID (e.g., a path) to produce an updated parent directory, dispersedstorage error encoding the updated parent directory to produce a set ofencoded updated parent directory slices, and sending the set of encodedupdated parent directory slices to the DSN memory for storage at aparent directory DSN address. The storage example of operation continueswith the step where the processing module dispersed storage errorencodes the updated directory file to produce a set of encoded updateddirectory slices. Next, the processing module sends the set of encodedupdated directory slices to the DSN memory for storage at a directoryDSN address.

As yet another example, a first set of chained directory files mayrepresent a directory structure for a first vault where the root addressstarts at a first DSN address and a second set of chained directoryfiles may represent the directory structure for the same first vault forthe root address starts at a second DSN address. Note that in thisexample the second set of chained directory files may be a redundantbackup copy of the directory of the first vault. Note that the firstand/or second DSN addresses may be predetermined and/or variable.Further note that the root address is critical to access the contents ofthe DSN memory, and as such, determination of or knowledge of the rootaddress is both critical for normal operation and can be a securityissue if available to unauthorized users. Note that multiple redundantdirectory copies may be stored in the DSN memory to further improve theoverall availability of the directory that they represent.

FIG. 7A is a diagram of another example of a dispersed storage networkdirectory structure that includes a directory address failsafe mechanism191, a root directories directory file 198, and a primary root directoryfile 200. The directory address failsafe mechanism 191 includes aplurality of agents 1-n and a share decoder 221. The root directoriesdirectory file 198 includes a file or directory name field 210 and adispersed storage network (DSN) address field 216. Note that the rootdirectories directory file 198 is accessed via a DSN address 204 (e.g.,3457). The primary root directory file 200 includes a file or directoryname field 212 and a DSN address field 218 and is accessed via a DSNaddress 204 (e.g., 0000).

The share decoder 221 may be implemented as part of a dispersed storage(DS) processing in any one of a user device, a DS processing unit, a DSmanaging unit, a storage integrity processing unit, and a DS unit. Forexample, the share decoder 221 may be implemented as a DS processing aspart of a DS processing unit to determine the root address of the rootdirectories directory file to enable access to data objects in a DSNmemory by utilizing information from a primary or redundant rootdirectory file. The agents 1-n may be implemented as part of a DSprocessing in any one of a user device, a DS processing unit, a DSmanaging unit, a storage integrity processing unit, and a DS unit. Forexample, the agents 1-n may be implemented as a DS processing in acombination of user devices and DS processing units. Each agent 1-nstores a share of a directory address that by itself does not reveal aDSN address of a directory file. A read threshold number of shares willenable the reproduction of the DSN address. For example, the shares areencoded data slices. As another example, the shares are Shamir sharedsecret shares.

In an example of operation, the share decoder 221 retrieves a thresholdnumber of the encoded components (e.g., shares 1−n) of the directoryaddress (e.g., 3457) from at least some of the plurality of agentmodules 1−n and reconstructs a directory address from the thresholdnumber of encoded components 1−n. For example, the share decoder 221reconstructs a directory address 204 (e.g., 3457) corresponding to theroot directories directory file 198. Alternatively, or in addition to,the share decoder 221 produces a directory file DSN address for one ormore other directory files (e.g., the primary root directory file 200,and intermediate directory file, and a directory file containing adesired filename). For example, the share decoder 221 produces the rootDSN address 206 (e.g., 0000) of the primary root directory file 200. Asanother example, the share decoder 221 produces a DSN address of 1000representing a DSN address of another directory file.

The root directories directory file 198 indicates the name of one ormore root directories (e.g., primary root directory) and one or more DSNaddresses of corresponding root directories (e.g., 0000). For example,the file or directory name field 210 includes the primary root directoryname and the DSN address field 216 includes the DSN address of 0000 tolink to the primary root directory file 200 by accessing DSN address0000. The primary root directory file 200 is accessed via DSN address206 (e.g., 0000) and includes file names or pathnames (e.g., /user,/bin, /home) in the file or directory name field 212 that link via DSNaddresses (e.g., 0010, 0020, 0030) in the DSN address field 218 tofurther directory files or data files.

FIG. 7B is a diagram of another example of a dispersed storage networkdirectory structure that includes a directory address failsafe mechanism196, a root directories directory file 198 of FIG. 7A, a primary rootdirectory file 200 of FIG. 7A, and a redundant root directory file 202.The directory address failsafe mechanism 196 includes a plurality ofagents 1-n of FIG. 7A, a share decoder 221 of FIG. 7A, and a shareencoder 222. The root directories directory file 198 of FIG. 7A includesa file or directory name field 210 and a dispersed storage network (DSN)address field 216. Note that the root directories directory file 198 isaccessed via a DSN address 204 (e.g., 3457). The primary root directoryfile 200 of FIG. 7A includes a file or directory name field 212 and aDSN address field 218 and is accessed via a DSN address 204 (e.g.,0000). The redundant root directory file 202 includes a file ordirectory name field 214 and a DSN address field 220 and is accessed viaa DSN address 208 (e.g., 1000).

The share decoder 221 operates as previously discussed with reference toFIG. 7A. The share encoder 222 may be implemented as part of a dispersedstorage (DS) processing in any one of a user device, a DS processingunit, a DS managing unit, a storage integrity processing unit, and a DSunit. For example, the share encoder 222 may be implemented as a DSprocessing as part of a DS processing unit to encode the root address ofthe root directories directory file to enable access to data objects ina DSN memory by utilizing information from a primary or redundant rootdirectory file. The agents 1−n operate to receive shares 1−n from theshare encoder 222 and to send shares 1−n to the share decoder 221.

In an example of operation, the share encoder 222 receives a directoryaddress of 3457 and dispersed storage error encodes the directoryaddress to produce a plurality of encoded components (e.g., shares 1−n)of the directory address (e.g., 3457). Next, the share encoder 222transmits the plurality of encoded components of the directory addressto a plurality of agent modules 1−n for storage therein. Alternatively,or in addition to, the share encoder 222 produces a directory file DSNaddress for one or more other directory files (e.g., the primary rootdirectory file 200, the redundant root directory file 202, anintermediate directory file, and a directory file containing a desiredfilename). For example, the share encoder 222 produces the root DSNaddress 208 (e.g., 1000) of the redundant root directory file 202.

In retrieval example of operation, the share decoder 221 retrieves athreshold number of the encoded components (e.g., shares 1−n) of thedirectory address (e.g., 3457) from at least some of the plurality ofagent modules 1−n and reconstructs a directory address from thethreshold number of encoded components 1−n. For example, the sharedecoder 221 reconstructs a directory address 204 (e.g., 3457)corresponding to the root directories directory file 198. Note that theroot directories directory file 198 indicates the name of one or moreroot directories (e.g., primary root directory, redundant rootdirectory) and one or more DSN addresses of corresponding rootdirectories (e.g., 0000, 1000). For example, the file or directory namefield 210 includes the primary root directory name and the DSN addressfield 216 includes the DSN address of 0000 to link to the primary rootdirectory file 200 by accessing DSN address 0000. As another example,the file or directory name field 210 includes the redundant rootdirectory name and the DSN address field 216 includes the DSN address of1000 to link to the redundant root directory file 202 by accessing DSNaddress 1000.

The redundant root directory file 202 is accessed via DSN address 208(e.g., 1000) and includes file names or pathnames in the file ordirectory name field 214, which are identical to the filenames and pathsnames in the file or directory name field to 12 of the primary rootdirectory file 200. The entries in the file or directory name field 214link via DSN addresses (e.g., 1010, 1020, 1030) in the DSN address field220 to further directory files or data files to replicate a directorystructure associated with the primary root directory file 200. Note thatthe DSN addresses in the DSN address field 220 of the redundant rootdirectory file 202 are different than the DSN addresses in the DSNaddress field 218 of the primary root directory file 200.

The redundant root directory file 202 is used when the primary rootdirectory 200 is unavailable or when one of the directory structures(e.g., file or directory name 210, DSN address 216) associated with theprimary root directory file 202 is damaged. The method of operation toutilize the primary or the redundant root directory file structures isdiscussed in greater detail preference to FIG. 9A.

FIG. 8A is a diagram of another example of a dispersed storage network(DSN) directory structure that includes a primary root directory file200, an intermediate directory file 150, and a file-level directory file152. The primary root directory file 200 includes a file or directoryname field 212 and a DSN address field 218 as previously discussed withreference to FIG. 7A. Such a primary root directory file 200 provides astart of a directory file structure linking to one or more intermediatedirectory files 150 and one or more file-level directory files 152. Theintermediate directory file 150 includes one or more intermediatedirectory entries 162 (e.g., file or directory name) and one or morecorresponding intermediate directory entry addresses 168 (e.g., a DSNaddress) for the one or more intermediate directory entries 162. Theintermediate directory file 150 is associated with an intermediatedirectory address 156 (e.g., 0010) to provide access to the intermediatedirectory file 150 stored in a DSN memory.

The file-level directory file 152 includes one or more file-leveldirectory entries 164 (e.g., a file name such as /user/temp/pic.jpg,/user/temp/picture.jpg) and one or more corresponding file-leveldirectory entry addresses 170 (e.g., 0019, 0100, 0078) to provide accessto the one or more file-level directory entries 164. The file-leveldirectory file 152 is associated with a file-level directory address 158(e.g., 0015), which is a DSN address.

In an example of obtaining a DSN address of a file (e.g.,/user/temp/picture.jpg) for file retrieval, the primary root directoryfile 200 is accessed at DSN root address 206 (e.g., DSN address 0000) byretrieving encoded data slices corresponding to the primary rootdirectory file 200 previously stored in the DSN memory and decoding theslices to produce the primary root directory file 200. The DSN addressof the intermediate directory file 150 (e.g., DSN address 0010) isextracted from the DSN address field 218 of the primary root directoryfile 200 corresponding to a file name portion /user entry of the file ordirectory name field 212. The intermediate directory file 150 isaccessed at the DSN intermediate directory address 156 (e.g., 0010). TheDSN address of the file-level directory file 152 (e.g., DSN address0015) is extracted from the DSN address field 168 of the intermediatedirectory file 150 corresponding to a file name portion /user/temp entryof the file or directory name field 162. The file-level directory file152 is accessed at the DSN file-level directory address 158 (e.g.,0015). The DSN address of the file name /user/temp/picture.jpg (e.g.,DSN address 0078) is extracted from the DSN address field 170 of thefile-level directory file 152 corresponding to a file name/user/temp/picture.jpg entry of the file or directory name field 164.The file name /user/temp/picture.jpg is accessed at the DSN address of0078) by retrieving encoded data slices corresponding to the file/user/temp/picture.jpg previously stored in the DSN memory and decodingthe slices to produce the file /user/temp/picture.jpg.

The directory structure represented in FIG. 8A is of a primary directoryfor a vault stored in the DSN memory. If any of the intermediatedirectory files along the path between the primary root directory fileand the address of the data file is missing, corrupted, or unavailable,or if any of the DSN addresses 206, 156, 152 of the directory files areunavailable, then accessing a desired data file stored in the DSN memorymay done using a redundant directory structure and/or providing amechanism to reproduce the DSN addresses of the directory filesindependent of associated directory file availability. Such structuresand/or mechanisms are discussed in greater detail with reference toFIGS. 8B, 8C, and 8D.

FIG. 8B is a diagram of another example of a dispersed storage network(DSN) directory structure where the directory structure provides aredundant directory structure and includes a redundant root directoryfile 202, and intermediate directory file 174, and a file-leveldirectory file 176. The redundant root directory file 202 includes afile or directory name field 214 and a DSN address field 220, which arethe same as the entries of the primary root directory file 200. Such aredundant root directory file 202 provides a start of a redundantdirectory file structure linking to one or more intermediate directoryfiles 174 and one or more file-level directory files 176.

The intermediate directory file 174 includes one or more intermediatedirectory entries 186 (e.g., file or directory name) and one or morecorresponding intermediate directory entry addresses 192 (e.g., a DSNaddress) for the one or more intermediate directory entries 186. Theintermediate directory file 174 is associated with an intermediatedirectory address 180 (e.g., 1010) to provide access to the intermediatedirectory file 174 stored in a DSN memory and includes the sameintermediate directory entries 186 as the intermediate directory entries162 of the intermediate directory file 150.

The file-level directory file 176 includes one or more file-leveldirectory entries 188 (e.g., file or directory name) and one or morecorresponding file-level directory entry addresses 194 (e.g., DSNaddress) providing access to the one or more file-level directoryentries 188. The one or more file-level directory entries 188 provideone or more redundant directory entries and are associated with one ormore corresponding redundant directory entry addresses 194 for the oneor more redundant directory entries 188. The file-level directory file176 is associated with a file-level directory address 182 (e.g., 1015)providing access to the file-level directory file 176 stored in the DSNmemory and includes the same file-level directory entries 188 as thefile-level directory entries 164 of the file-level directory file 152.The DSN address field 194 includes DSN addresses of subsequent directoryfiles and/or DSN addresses of files, which are identical to the DSNaddress entries 170 of the primary root-to-file path. For example,file-level directory file 176 indicates that thefile/user/temp/picture.jpg is stored at DSN address 0078 and file-leveldirectory file 152 indicates that the file/user/temp/picture.jpg isstored at DSN address 0078.

In an example of obtaining a DSN address of a file (e.g.,/user/temp/picture.jpg) utilizing the redundant directory structure forretrieval, the redundant root directory file 202 is accessed at DSN rootaddress 206 (e.g., DSN address 1000) by retrieving encoded data slicescorresponding to the redundant root directory file 202 previously storedin the DSN memory and decoding the slices to produce the redundant rootdirectory file 202. The DSN address of the intermediate directory file174 (e.g., DSN address 1010) is extracted from the DSN address field 220of the redundant root directory file 202 corresponding to a file nameportion /user entry of the file or directory name field 214.

The intermediate directory file 174 is accessed at the DSN intermediatedirectory address 180 (e.g., 1010). The DSN address of the file-leveldirectory file 176 (e.g., DSN address 1015) is extracted from the DSNaddress field 192 of the intermediate directory file 174 correspondingto a file name portion /user/temp entry of the file or directory namefield 186. The file-level directory file 176 is accessed at the DSNfile-level directory address 182 (e.g., 1015). The DSN address of thefile name /user/temp/picture.jpg (e.g., DSN address 0078) is extractedfrom the DSN address field 194 of the file-level directory file 176corresponding to a file name /user/temp/picture.jpg entry of the file ordirectory name field 188. The file name /user/temp/picture.jpg isaccessed at the DSN address of 0078) by retrieving encoded data slicescorresponding to the file /user/temp/picture.jpg previously stored inthe DSN memory and decoding the slices to produce the file/user/temp/picture.jpg.

In the example of FIG. 8B, the directory structure is of a redundantdirectory for a vault stored in the DSN memory. In another example, oneor more redundant directories may be used to provide an accessavailability improvement to the system when a primary directory is notavailable. For instance, one or more redundant directories are utilizedwhen the primary directory is not available and/or when one or moreredundant directories are not available.

FIG. 8C is a diagram of another example of a dispersed storage networkdirectory structure that includes the primary root directory file 200,the intermediate directory file 150, and the file-level directory file152 of FIG. 8A and a directory address failsafe mechanism 196 of FIG.7B. The directory address failsafe mechanism 196 dispersed storage errorencodes one or more of a plurality of directory addresses (e.g., a rootdirectory address 206, and intermediate directory address 156, and afile-level directory address 158) to produce one or more sets of aplurality of encoded components and transmits the plurality of encodedcomponents to a plurality of agent modules. For example, a first set ofa plurality of encoded components corresponds to a root directoryaddress, a second set of a plurality of encoded components correspondsto an intermediate directory address, and a third set of a plurality ofencoded components corresponds to a file-level directory address. Forinstance, the directory address failsafe mechanism 196 dispersed storageerror encodes the intermediate directory address 156 (e.g., DSN address0010) to produce a plurality of encoded components of the intermediatedirectory address and transmits the plurality of encoded components ofthe intermediate directory address 156 to a plurality of agent modules.As another example, a set of a plurality of encoded componentscorresponds to an aggregate of the root directory address, theintermediate directory address, and the file-level directory address.

The directory address failsafe mechanism 196 reproduces any of thedirectory addresses by retrieving at least a threshold number of theencoded components from the plurality of agent modules and dispersedstorage error decodes the at least the threshold number of encodedcomponents to produce the directory address. The directory address isutilized to access a directory file.

FIG. 8D is a diagram of another example of a dispersed storage networkdirectory structure that includes the primary root directory file 200,the intermediate directory file 150, and the file-level directory file152 of FIG. 8A and a directory address failsafe mechanisms 193, 195, and197. The directory address failsafe mechanisms 193, 195, and 197 operateas previously discussed with reference to the directory address failsafemechanism 196 of FIG. 7B to provide a directory address backup for onedirectory file per directory address failsafe mechanism. The directoryaddress failsafe mechanisms 193, 195, and 197 dispersed storage errorencodes a directory addresses (e.g., a root directory address 206, andintermediate directory address 156, and a file-level directory address158) to produce a plurality of encoded components and transmits theplurality of encoded components to a plurality of agent modulesassociated with a directory address.

In this example, directory address failsafe mechanism 193 dispersedstorage error encodes the primary root directory address to produce aplurality of encoded components of the primary root directory addressand transmits the plurality of encoded components of the primary rootdirectory address to a plurality of primary root directory agentmodules; Directory address failsafe mechanism 195 dispersed storageerror encodes the intermediate directory address to produce a pluralityof encoded components of the intermediate directory address andtransmits the plurality of encoded components of the intermediatedirectory address to a plurality of intermediate directory agentmodules; and Directory address failsafe mechanism 197 dispersed storageerror encodes the file-level directory address to produce a plurality ofencoded components of the file-level directory address and transmits theplurality of encoded components of the file-level directory address to aplurality of file-level directory agent modules.

The directory address failsafe mechanisms 193, 195, and 197 reproduces acorresponding one of the directory addresses by retrieving at least athreshold number of the encoded components from the plurality ofassociated agent modules and dispersed storage error decodes the atleast the threshold number of encoded components to produce thedirectory address. The directory address is utilized to access acorresponding directory file. For example, directory address failsafemechanism 195 retrieves at least a threshold number of the encodedcomponents of the plurality of encoded components of the intermediatedirectory address from the plurality of intermediate directory agentmodules and dispersed storage error decodes the at least the thresholdnumber of encoded components to reproduce the intermediate directoryaddress (e.g., DSN address 0010).

FIG. 9A is a flowchart illustrating an example of accessing directoryinformation where the method begins with step 223 where a processingmodule receives a file access request. Such a file access requestincludes one or more of a requester identifier (ID), a data ID, a filename, a directory file path, a block ID, a performance requirement, anaccess reliability requirement, and an access type. The access typeincludes at least one of a read data request, a write data request, alist request, a delete request, a modify request, and a replacementrequest. The method continues at step 225 where the processing moduleidentifies a directory file path based on the file access request. Forexample, the processing module extracts a directory file path of/user/temp/picture.jpg from the file access request.

The method continues at step 227 where the processing module determineswhether the directory file path exists (e.g., it was previouslyestablished and stored in a dispersed storage network (DSN) memory). Theprocessing module determines that the directory file path exists whenthe processing module discovers a memory-based directory file path thatcompares favorably to the directory file path of the request. Forexample, the processing module determines that the directory file pathexists when the processing module receives a read request for thedirectory file path of file /user/temp/picture.jpg and accesses the DSNmemory to determine that a memory-based directory file path comparesfavorably to the directory file path to (e.g., exists). As anotherexample, the processing module determines that the directory file pathdoes not exist when the processing module receives a write request forthe directory file path of /user/temp/picture.jpg and accesses the DSNmemory determine that a memory-based directory file path does notcompare favorably to the directory file path (e.g., it does not existyet). The method branches to step 231 when the processing moduledetermines that the directory file path does not exist. The methodcontinues to step 229 when the processing module determines that thedirectory file path does not exist. At step 229, the processing modulecreates the directory file path when the directory file path does notexist.

The method continues at step 231 where the processing module determineswhether to create a redundant directory file path. Such a determinationmay be based on one or more of the performance requirement, the accessreliability requirement, the requester ID, and the access type. Forexample, the processing module determines to create the redundantdirectory file path when the access reliability requirement indicatesthat a level of required access reliability is greater than an accessreliability threshold. The method branches to step 235 where theprocessing module determines not to create the redundant directory filepath. The method continues to step 233 when the processing moduledetermines to create the redundant directory file path. At step 233, theprocessing module creates the redundant directory file path.

At step 235 the processing module determines whether a directory address(e.g., a DSN address) of a directory file of the directory file path isavailable based on accessing the DSN memory; where the directory fileincludes at least one of a root directory file, an intermediatedirectory file, and a file-level directory file. The method branches tostep 247 when the processing module determines that the directoryaddress is available. The method continues to step 237 when theprocessing module determines that the directory address is notavailable. At step 237, the processing module determines whether toreconstruct the directory address or to use a redundant directory filepath. Such a determination may be based on one or more of agent moduleavailability, the requester ID, the data ID, the file name, thedirectory file path, the block ID, the performance requirement, theaccess reliability requirement, and the access type. For example, theprocessing module determines to reconstruct the directory address whenthe agent module availability is favorable (e.g., the agent modulescontain shares of the directory address). As another example, theprocessing module determines to use the redundant directory file pathwhen the performance requirement indicates that low access latency isrequired.

The method branches to step 243 when the processing module determines toreconstruct the directory address. The method continues to step 239 whenthe processing module determines to use the redundant directory filepath (e.g., to not reconstruct the directory address). At step 239, theprocessing module determines one or more directory addresses for one ormore redundant directory files in the redundant directory file pathbased on accessing the redundant directory file path from the DSNmemory. The method continues at step 241 where the processing moduleaccesses a file via the one or more directory addresses of the redundantdirectory file path. For example, the processing module retrieves aplurality of sets of encoded data slices from a file DSN addressextracted from a directory address of the redundant directory file pathand dispersed storage error decodes the plurality of sets of encodeddata slices to reproduce the file.

The method continues at step 243 where the processing module retrievesencoded components of the directory address from a plurality of agentmodules when reconstructing the directory address. The method continuesat step 245 where the processing module reconstructs the directoryaddress from the at least a threshold number of the encoded componentsof the directory address when at least a threshold number of the encodedcomponents of the directory address have been received. The methodcontinues at step 247 where the processing module accesses the file viathe directory address. For example, the processing module retrieves theplurality of sets of encoded data slices from the file DSN addressextracted from the directory address and dispersed storage error decodesthe plurality of sets of encoded data slices to reproduce the file.

FIG. 9B is a flowchart illustrating an example of retrieving directoryinformation. The method begins at step 224 where a processing moduledetermines agents containing shares. Such a determination may be basedon one or more of: agent entries by a user, a lookup, apredetermination, a query of agents, a command, a message, an email, anda memory device access. For example, the processing module determinesagents based on a list of agents contained in a memory of a dispersedstorage (DS) processing unit.

The method continues at step 226 where the processing module sends ashare request message to at least a read threshold number of the agentswhere the message includes one or more of a request to send the shareassociated with the agent back to the DS processing, a user identifier(ID), a vault ID, a data object name, a source name, a slice name, and aroot directory file name. The method continues at step 228 where theprocessing module receives share information from one or more agents inresponse to the share request message. Note that the shares may includean encoded data slice and/or a Shamir share of a shared secret.

The method continues at step 230 where the processing module determinesoperational parameters (e.g., dispersed storage error coding parameters)to enable decoding the shares. Such a determination may be based on oneor more of a user ID, a vault ID, a vault lookup, a message, a command,a predetermination, a data object name, a source name, a slice name, anda root directory file name. Next, the processing module de-slices anddecodes at least a read threshold number of shares in accordance withthe operational parameters to produce a dispersed storage network (DSN)address of a root directories directory file when a share format isencoded data slices. Alternatively, the processing module decodes atleast a read threshold number of shares in accordance with theoperational parameters to produce the DSN address of the rootdirectories directory file when the share format is shares of a sharedsecret.

The method continues at step 232 where the processing module retrievesthe root directories directory file based on the DSN address of the rootdirectories directory file. For example, the processing module convertsthe DSN address of the root directories directory file into slice names.Next, the processing module determines physical storage locations of theencoded data slices of the root directories directory file based on theslice names and a lookup in a DSN address to physical location table.The processing module determines operational parameters of the rootdirectories directory file based on a vault ID associated with the rootdirectories directory file and a vault lookup. The processing modulesends retrieve slice commands to DS units and receives encoded dataslices in response. The processing module de-slices and decodes theencoded data slices in accordance with the operational parameters of theroot directories directory file to produce the data segments of the rootdirectories directory file. The processing module aggregates the datasegments to produce the root directories directory file. Note that theprocessing module may temporarily cache the root directories directoryin a local memory.

The method continues at step 234 where the processing module determinesa root directory address of a desired root directory (e.g., a primaryroot directory and/or a redundant root directory) based on one or moreof the contents of the root directories directory file, what may havealready failed in a previous directory retrieval attempt, and whatdirectory file has not been tried so far. For example, the processingmodule tries the redundant root directory file when the primary rootdirectory file is not available. As another example, the processingmodule tries a second redundant root directory file when a firstredundant root directory file is not available.

The method continues at step 236 where the processing module retrievesroot directory information based on accessing the DSN memory at a DSNaddress of the desired root directory. For example, the processingmodule converts the DSN address of the root directory file into slicenames. The processing module determines physical locations of encodeddata slices of the root directory file based on the slice names and alookup in the DSN address to physical location table. The processingmodule determines operational parameters of the root directory filebased on a vault ID associated with the root directory file and a vaultlookup. The processing module sends retrieve slice commands to the DSunits and receives encoded data slices in response. The processingmodule de-slices and decodes the encoded data slices from at least aread threshold number of pillars in accordance with the operationalparameters of the root directory file to produce data segments of theroot directory file. The processing module aggregates the data segmentsto reproduce the root directory file. The process repeats as theprocessing module retrieves further linked directory files from the rootdirectory file until the desired DSN address is determined correspondingto a path name of a desired data object. Note that the processing modulemay temporarily cache the root directory file and a directory structureassociated with the root directory file in a local memory.

FIG. 10 is a diagram illustrating an example of manager informationstructure 238 that includes information created and subsequentlyutilized by a dispersed storage (DS) managing unit to organize theinformation used to facilitate operation of a dispersed storage network(DSN) system. The manager information 238 includes standard information240 and sensitive information 242, wherein sensitive information 242includes information associated with accessing a vast portion of datacontained in the DSN system and wherein the standard information 240 isutilized to gain access to lesser portions of the data contained in theDSN system.

The DS managing unit has access to the manager information 238 andshould be available to provide the manager information 238 to the DSmanaging unit when needed. To ensure that a DS managing unit isavailable, a new DS managing unit is activated when a current DSmanaging unit fails. Such an activation of the new DS managing unitincludes recovering and installing the manager information 238 such thatthe new DS managing unit can take over the functions of the DS managingunit.

The standard information 238 includes one or more of accounts and/orcredentials 244, vault lists 246, vault access controls 248, registryinformation 250, and certificate authority private key information 252.The accounts and/or credentials 244 include a list of user identifiers(IDs) and/or authorization levels for various available functions withinthe DSN system; the vault lists 246 includes vault ID's and/orcorresponding user IDs associated with vaults within the DSN system; thevault access controls 248 lists user IDs and/or user groups that areauthorized to access specific vaults; the registry information 250includes a list of file directories and/or lists of units and functionsassociated with the DSN system; and the certificate authority (CA)private key 252 includes one or more encryption keys utilized to decryptencrypted messages sent to the DS managing unit, one or more keysutilized to encrypt messages that the DS managing unit sends to otherunits and/or functions of the DSN system, and may include receivedcertificates from a certificate authority that authorized the DSmanaging unit and other units of the system to exchange information inconfidence. The sensitive information 242 includes one or more managerhost keys 254. Such a manager host key 254 is utilized to access atleast a portion of the manager information and/or to execute functionsof the DS managing unit.

In an operational scenario example, a first DS managing unit stores aredundant copy of the standard information 240 as a first set of encodeddata slices in the DSN memory and stores a redundant copy of thesensitive information 242 as a second set of encoded data slices in theDSN memory. Next, a second DS managing unit is activated when the firstDSN managing unit fails. The second DS managing unit contacts aplurality of agents to retrieve shares of a secret share to decode a DSNaddress leading to the second set of encoded data slices that containsthe manager host key 254. The second DS managing unit determines themanager host key 254 based on retrieving the second set of encoded dataslices. The second DS managing unit retrieves the first set of encodeddata slices from the DSN memory to recover the redundant copy of thestandard information 240. The second DS managing unit becomes fullyoperational as an operating DS managing unit of the system when thestandard information 240 has been successfully loaded. A method to storeand retrieve a copy of the manager host key 254 is discussed in greaterdetail with reference to FIG. 12-13.

In addition to, or in the alternative of, sharing secret shares of themanager information, it may be redundantly stored in portions and in adistributed fashion in the DSN memory. In this instance, if a portion ofthe manager information 238 is not readily available, a redundant copyof the portion of the manager information 238 may be retrieved and used.

As an alternative to redundantly storing all of the manager information238, the DS managing unit stores a redundant copy of the standardinformation 240 in the DSN memory but not a redundant copy of thesensitive information 242 to provide a balance between reliability andsecurity of the manager information. In an operational scenario example,a first DS managing unit stores a redundant copy of the standardinformation 240 as encoded data slices in the DSN memory but not of thesensitive information 242. A second DS managing unit is activated whenthe first DSN managing unit fails. A manager host key is entered intothe second

DS managing unit enabling the second DS managing unit to access theredundant copy of the standard information 242 from the DSN memory. Thesecond DS managing unit becomes fully operational as the DSN managingunit of the system when the standard information 240 has beensuccessfully loaded. A method to store the standard information isdiscussed in greater detail with reference to FIG. 11.

FIG. 11 is a flowchart illustrating an example of storing managerinformation. A method begins with step 256 where a processing moduledetermines to backup manager information. Such a determination may bebased on one or more of a schedule, a command, a predetermination, alist, a message, elapsed time since the last backup, a change indicator,a dispersed storage network (DSN) memory status indicator, and a newdispersed storage (DS) managing unit activation indicator. For example,the processing module determines to backup the manager information whena change in the manager information is detected as indicated by a changeindicator.

The method continues at step 258 where the processing module determinesstandard information of the manager information. Such a determinationmay be based on one or more of a command, a predetermination, a list, amessage, a command, elapsed time since the last backup, a changeindicator, a DSN memory status indicator, a new DS managing unitactivation indicator and a security indicator. For example, theprocessing module determines the standard information as a list of itemsfrom local memory as illustrated in FIG. 10.

The method continues at step 260 where the processing module gathers thestandard information from one or more of DS managing unit local memory,DSN memory, a storage integrity processing unit, a user device, a DSprocessing unit, and a DS unit. The method continues at step 262 wherethe processing module determines operational parameters (e.g., dispersedstorage error coding parameters) based on one or more of a DS managingunit identifier (ID), a vault lookup, a list, a command, a message, anda predetermination. The method continues at step 264 where theprocessing module determines a DS unit storage set, which contains theDS units that will be utilized to store the pillars of encoded dataslices of a backup copy of the standard information. Such adetermination may be based on one or more of a vault lookup, a DSmanaging unit ID, a list, a command, a message, a predetermination, theoperational parameters, and a DSN memory status indicator.

The method continues at step 266 where the processing module dispersedstorage error and codes the standard information in accordance with theoperational parameters to produce encoded data slices of the standardinformation. The method continues at step 268 where the processingmodule sends the encoded data slices to the DS unit storage set with astore command such that the DS units of the DS unit storage set storethe encoded data slices in the memory of the DS units in response to thestore command.

In an example of a subsequent standard information retrieval method, theprocessing module receives a restore manager information command and amanager host key from one or more of a user input, a user device, a DSprocessing unit, a storage integrity processing unit, a DS managingunit, and a DS unit. The processing module determines the DS unitstorage set based in part on a manager ID, a manager vault ID, and avault lookup. The processing module sends a retrieve slice command tothe DS units of the DS unit storage set. The processing module receivesencoded data slices in response to the retrieval commands and re-createsthe standard information in accordance with operational parameters forthe manager information. The processing module stores the managerinformation in the memory of the DS managing unit where it may beutilized in subsequent operations of the DS managing unit.

FIG. 12 is a flowchart illustrating an example of storing a manager hostkey. A method begins with step 270 where a processing module determinesto backup the manager host key. Such a determination may be based on oneor more of a schedule, a command, a predetermination, a list, a message,elapsed time since the last backup, a change indicator, a dispersedstorage network (DSN) memory status indicator, and a new dispersedstorage (DS) managing unit activation indicator. For example, theprocessing module determines to backup the manager host key when theprocessing module determines that the elapsed time since the last backupof the manager key exceeds a threshold.

The method continues at step 272 where the processing module encodes themanager host key to produce a plurality of manager host key shares basedin part on at least one of but not limited to the manager host key and ashare method. Note that the share method may include one or more of aShamir secret share method (e.g., creating shares with an associateddecode threshold) and/or distributed storage method (e.g., creatingencoded data slices with an associated decode threshold). Further notethat a property of the share method includes re-creation of the originalmanager host key only when a decode threshold number of shares areavailable. As such, a share by itself does not contain enoughinformation to determine the manager host key.

The method continues at step 274 where the processing module determinesa plurality of manager host key share agents where shares will besubsequently stored based on one or more of a vault lookup, a DSmanaging unit identifier (ID), a list, a command, a message, apredetermination, a query of candidate share agents, and share agentavailability information. Note that the agents may include anotherprocessing module implemented in one or more of a user device, the DSprocessing unit, a storage integrity processing unit, a DS managingunit, and a DS unit. For example, the processing module determines theplurality of manager host key share agents to be a plurality of userdevices. As another example, the processing module determines theplurality of manager host key share agents to include user devices andDS processing units.

The method continues at step 276 where the processing module encryptsthe plurality of manager host key shares to produce a plurality ofencrypted manager host key shares in accordance with one or more of apublic key associated with each of the plurality of manager host keyshare agents, a secret key, a private key, a public key, and/oroperational parameters. Note that the key may be associated with thehost key share agent. For example, a share is uniquely encrypted withthe public key associated with an agent 2 that the encrypted share willbe sent to for storage.

The method continues at step 278 where the processing module sends theplurality of encrypted manager host key shares with a store command tothe plurality of manager host key share agents to store the plurality ofencrypted manager host key shares. For example, the processing modulesends the manager host key shares utilizing an email scheme where targetemail addresses are associated with the manager host key share agents.

As yet another operational example, the manager host key agent receivesthe encrypted share and decrypts the encrypted share in accordance witha private key associated with a public/private key pair of the managerhost key agent where the public key was previously utilized to encryptthe share to produce the encrypted share. The host key agent stores theshare in memory and subsequently retrieves the share from memory,encrypts the share to produce an encrypted share, and send the encryptedshare to a processing module in response to receiving a manager host keyshare request from the processing module.

In a further operational example, the manager host key agent receivesthe encrypted share and stores the encrypted share in memory. The hostkey agent subsequently retrieves the encrypted share from memory,decrypts the encrypted share in accordance with a private key associatedwith a public/private key pair of the manager host key agent where thepublic key was previously utilized to encrypt the share to produce theencrypted share, encrypts the share to produce an encrypted share, andsends the encrypted share to a processing module in response toreceiving a manager host key share request from the processing module.

FIG. 13 is a flowchart illustrating an example of retrieving a managerhost key. A method begins with step 280 where a processing moduledetermines to recover the manager host key. Such a determination may bebased on one or more of a schedule, a command, a predetermination, alist, a message, elapsed time since the last backup, elapsed time as thelast recovery, a change indicator, a dispersed storage network (DSN)memory status indicator, an error message, and a new dispersed storage(DS) managing unit activation indicator. For example, the processingmodule determines to restore the manager host key when the processingmodule determines that a new DS managing unit is active based on the newDS managing unit activation indicator.

The method continues at step 274 (as described in FIG. 12) and continuesat step 284 where the processing module sends a share retrieval messageto a plurality of manager host key share agents to retrieve a pluralityof encrypted manager host key shares. For example, the processing modulesends the retrieval message to the agents within an email message. Themanager host key share agents retrieve the manager host key shares fromthe memory of the manager host key share agents, encrypt the managerhost key shares in accordance with an encryption method associated withthe processing module (e.g., a public key of a public/private key pairassociated with the processing module), and send the encrypted host keyshares to the processing module. In an instance, the agent sends sendthe response message to the processing module within an email message.

The method continues at step 286 where the processing module receives aplurality of encrypted manager host key shares from the manager host keyshare agents in response to the share retrieval messages. Note that atleast a decode threshold number of shares are required to re-create themanager host key. The method continues at step 288 where the processingmodule decrypts the plurality of encrypted manager host key shares toproduce a plurality of manager host key shares in accordance with one ormore of a private key associated with the DS managing unit, a keyassociated with each of the plurality of manager host key share agents,a secret key, a private key, and a public key. For example, theprocessing module decrypts the encrypted host key share utilizing aprivate key of a private/public key pair of the processing module and/orthe DS managing unit.

The method continues at step 290 where the processing module decodes theplurality of manager host key shares utilizing at least a read thresholdnumber of shares to produce the manager host key in accordance with oneor more of a share method, a manager ID, a vault ID, operationalparameters, a vault lookup, a command, a message, and apredetermination. Note that the processing module may store the managerhost key in local memory associated with the processing module and/orthe DS managing unit.

FIG. 14 is a flowchart illustrating an example of associating accesscontrol information with an encoded data slice. The method begins atstep 292 where a processing module receives a data storage request thatincludes data. Such a data storage request message may include one ormore of a user identifier (ID), data, a data object name, a data type, adata object, input access control information, a priority indicator, asecurity indicator, and a performance indicator. The method continueswith step 262 of FIG. 11 and then at step 296 where the processingmodule dispersed storage error encodes the data in accordance with thedispersed storage error encoding parameters to produce a set of encodeddata slices.

The method continues at step 298 where the processing module establishesaccess control information for each encoded data slice of the setencoded data slices in accordance with the dispersed storage errorencoding parameters to produce a set of access control information(i.e., each slice has its own access control information). The accesscontrol information includes at least one of: a requester ID allowed toaccess the data, a requester ID disallowed to access the data, arequester ID allowed to access an encoded data slice of the set ofencoded data slices associated with an allowed slice name, a requesterID disallowed to access the encoded data slice of the set of encodeddata slices associated with a disallowed slice name, and an access typeindicator (e.g., read, store, replace, modify, delete, list, rebuild).

The processing module may establish the set of access controlinformation by extracting the set of access control information from thedata storage request and/or retrieving the set of access controlinformation based on at least one of a data ID, a user device ID, a datatype, an analysis of the data, a priority indicator, a securityindicator, a performance indicator, a vault lookup, a list, a command, amessage, and a predetermination. Alternatively, or in addition to, theprocessing module may query a dispersed storage (DS) managing unit basedon the data ID and the user device ID to retrieve the set of accesscontrol information.

From a set perspective, the access control information grants access toone or more specific requesting units to at least a decode thresholdnumber of encoded data slices; denies access to one or more specificrequesting units for at least a pillar width number minus the decodethreshold number of encoded data slices; grants access to a specificrequesting code for at least the decode threshold number of encoded dataslices; grants read-only access to one or more specific requesting unitsfor at least the decode threshold number of encoded data slices. Forexample, the DS processing determines the access control information toinclude an indicator that the user ID 754 is authorized to access theslice name 5396 for the purpose of reading the slice but not for thepurposes of modification or deletion.

The method continues at step 300 where the processing module appends acorresponding one of the set of access control information to one of theset of encoded data slices to produce a set of appended slices (e.g.,each data slice has appended thereto its own access controlinformation). The processing module may append the access controlinformation to the beginning of an encoded data slice; to the end of theencoded data slice; or by embedding the access control informationwithin the encoded data slice.

The method continues at step 302 where the processing module determinesa set of DS units. Such a determination may be based on one or more of auser ID, a vault ID, a vault lookup, a list, a command, a message, apredetermination, the dispersed storage error encoding parameters, theset of appended slices, the access control information, and a dispersedstorage network (DSN) memory status indicator. The method continues atstep 304 where the processing module outputs the set of appended slicesto the set of DS units.

FIG. 15 is a flowchart illustrating an example of authenticating anencoded data slice access request. The method begins with step 306 wherea processing module receives a slice access request message. Note thatthe access slice access request message may include one or more of aslice name, a type of access request (e.g., read, store, replace,modify, delete, list, rebuild), a requester identifier (ID), a slicename range, a source name, a dispersed storage network (DSN) virtualaddress, a user ID, a requester ID, a data object name, a data type,input access control information, a priority indicator, a securityindicator, and a performance indicator. The method continues at step 308where the processing module determines a requester based on one or moreof information in the slice access request message (e.g., a requesterID), a lookup, a command, a message, a predetermination, and a list.

The method continues at step 310 where the processing module obtainsaccess control information based on at least one of the slice name andthe requestor ID. Such obtaining of the access control informationincludes at least one of retrieving the access control information froma memory based on the slice name and sending an access controlinformation request message to a dispersed storage (DS) managing unit,wherein the access control information request message includes theslice name, and receiving an access control information responsemessage, wherein the access control information response messageincludes the access control information. For example the processingmodule determines a location of the access control information based ona lookup of a local virtual DSN address to physical location table.Next, the processing module retrieves the access control informationfrom a memory of a DS unit at the location of the access controlinformation.

The method continues at step 312 where the processing module determineswhether the slice access request message is allowable based on theaccess control information. Such a determination includes at least oneof determining that the requester ID is allowed access to the encodeddata slice, determining that the requester ID is not allowed access tothe encoded data slice, determining that the requester ID is allowedaccess to the encoded data slice for the type of access request, anddetermining that the requester ID is not allowed access to the encodeddata slice for the type of access request. For example, the processingmodule determines the slice access request message is allowable when theaccess control information includes an indicator that user ID 754 isauthorized to access slice name 5396 for the purpose of reading theslice but not for the purposes of modification or deletion and the sliceaccess request message includes user ID 754 requesting a read type ofaccess request to read an encoded data slice with a slice name 5396. Asanother example, the processing module determines the slice accessrequest message is not allowable when the access control informationincludes an indicator that the user ID 754 is authorized to access theslice name 5396 for the purpose of reading the slice but not for thepurposes of modification or deletion and the slice request messageincludes user ID 754 requesting a delete type of access request of theencoded data slice with the slice name 5396.

The method branches to step 316 when the processing module determinesthat the slice access request message is allowable. The method continuesto step 314 when the processing module determines that the slice accessrequest message is not allowable. The method continues at step 314 wherethe processing module outputs a slice access denial response message.For example, the processing module sends the slice access denialresponse message to a DS managing unit when the processing moduledetermines that the slice access request message is not allowable.

The method continues at step 316 where the processing module accesses anencoded data slice of a set of encoded data slices in accordance withthe slice access request message when the slice access request messageis allowable. Such accessing of the encoded data slice of the set ofencoded data slices comprises at least one of retrieving the encodeddata slice based on the slice name and outputting the encoded dataslice, extracting a replacement slice from the slice access requestmessage and replacing the encoded data slice affiliated with the slicename with the replacement slice, extracting the encoded data slice fromthe slice access request message and storing the encoded data slice(e.g., replacing, updating), deleting the encoded data slice based onthe slice name, and retrieving slice attributes associated with theencoded data slice based on the slice name and outputting the sliceattributes. For example, the processing module retrieves an encoded dataslice with a slice name 5396 and outputs the encoded data slice to arequester when the slice access message is allowable.

FIG. 16 is a flowchart illustrating an example of modifying a deliveredservice level. A processing module determines a delivered service levelprovided to at least one user identifier (ID) and/or user device andmodifies parameters of a dispersed storage network (DSN) system toaffect a future delivered service level based in part on the deliveredservice level. Such a service level may include one or more of accesslatency, access bandwidth, available storage, actual utilized storage,system availability, system reliability, and security performance (e.g.,intrusions, corrupted information, hacked information, etc.) Theprocessing module may be implemented in one or more of a dispersedstorage (DS) managing unit, a user device, a DS processing unit, astorage integrity processing unit, and a DS unit.

The method begins at step 320 where the processing module determines adelivered service level to at least the user identifier (ID) and/or userdevice based on one or more of a query, a message, a user ID, a userdevice ID, a measurement, a list, a performance analysis, a historicalrecord, and the error message, and a transaction record. Note that theprocessing module may determine which user and/or user device todetermine the service level for based on one or more of a command, alist, a message, a recent transaction, an error message, and the lastuser ID that was examined. For example, the processing module determinesto examine the next user ID and a list.

The method continues at step 322 where the processing module determinesone or more thresholds for comparison to of the delivered service level.Such a determination may be based on one or more of a user ID, a userdevice ID, a vault ID, a vault lookup, a list, a predetermination, acommand, a message, and a DSN memory status indicator. The methodcontinues at step 324 where the processing module determines whether thedelivered service level compares favorably to the one or morethresholds. Such a determination may be based on one or more of thedelivered service level, the thresholds, a comparison of the deliveredservice level to the thresholds, a command, a message, and a DSN memorystatus indicator. Note that the processing module determines that theoutcome is unfavorable when the DSN system is over performing orunderperforming with respect to service level expectations of a user asindicated by thresholds associated with the user. For example, theprocessing module determines that the DSN system is underperforming whenthe processing module determines that the access latency performance isgreater than an access latency performance threshold (e.g., too slow).As another example, the processing module determines that the DSN systemis over performing when the access latency performance is less than theaccess latency performance threshold (e.g., too fast). Note that theprocessing module determines a favorable comparison when the DSN systemis performing within a desired range of thresholds.

The method repeats back to step 320 when the processing moduledetermines that the delivered service level compares favorably to theone or more thresholds. The method branches to step 332 when theprocessing module determines that the delivered service level does notcompare favorably to the one or more thresholds and the DSN system isover performing. The method continues to step 326 when the processingmodule determines that the delivered service level does not comparefavorably to the one or more thresholds and the DSN system isunderperforming.

The method continues at step 326 where the processing module determinesa correction to raise the delivered service level based on one or moreof the delivered service level, the thresholds, a comparison of thedelivered service level to the thresholds, a command, a message, a DSNmemory status indicator, and a correction history. Such a correction mayinclude assigning more favorable resources to the user for futureactivities to improve performance and may include assigning lessfavorable resources to other users which may indirectly improve theperformance to the user (e.g., the DSN system is less burdened with theother users and may provide better service to the user). Nothingcontinues at step 328 where the processing module assigns more favorableresources to the user where the more favorable resources may include oneor more of more DS processing units, different DS processing units withlower access latency and/or with more capacity, more DS units, anddifferent DS units with lower access latency and/or with more capacity.The method continues at step 330 where the processing module assignsless favorable resources to other users wherein the less favorableresources may include one or more of fewer DS processing units,different DS processing units with higher access latency and/or withless capacity, fewer DS units, and different DS units with higher accesslatency and/or with less capacity.

The method continues at step 332 where the processing module determinesa correction to lower the delivered service level based on one or moreof the delivered service level, the thresholds, a comparison of thedelivered service level to the thresholds, a command, a message, a DSNmemory status indicator, and a correction history. Such a correction mayinclude assigning less favorable resources to the user for futureactivities to lower the performance and may include assigning morefavorable resources to other users which may indirectly lower theperformance to the user (e.g., the DSN system is more burdened with theother users and may provide lowered service to the user).

The method continues at step 334 where the processing module assignsless favorable resources to the user where the less favorable resourcesmay include one or more of fewer DS processing units, different DSprocessing units with higher access latency and/or with less capacity,fewer DS units, and different DS units with higher access latency and/orwith less capacity. The method continues at step 336 where theprocessing module assigns more favorable resources to other users wherethe more favorable resources may include one or more of more DSprocessing units, different DS processing units with lower accesslatency and/or with more capacity, more DS units, and different DS unitswith lower access latency and/or with more capacity.

FIG. 17A is a schematic block diagram of another embodiment of acomputing system that includes a user device 13 and a cloud storagesystem 357. The user device 13 includes a computing core 26 and aninterface 30. The cloud storage system 357 includes a dispersed storage(DS) processing unit 16 and a dispersed storage network (DSN) memory 22.

In an example of operation, the user device 13 sends a data file 38 anda data storage request 337 to the cloud storage system 357. In addition,user device 13 specifies reliability factors, which include a cloudstorage access reliability indication 339 and a cloud storage datareliability indication 341. The cloud storage access reliabilityindication 339 includes at least one of a level of availability of dataof the data storage request (e.g., a number of redundant copies, anumber of memory devices, a number of sites, a downtime tolerancelevel), storage cost information (e.g., data unavailability costconsequence, storage transfer costs), a redundant array of independentdisks (RAID) preference indicator, and a data dispersal preferenceindicator. The cloud storage data reliability indication 341 includes atleast one of a data loss cost consequence, a data loss tolerance level(e.g., a number of redundant copies, a number of memory devices, anumber of sites), the storage cost information, the RAID preferenceindicator, and the data dispersal preference indicator. The user devicemay determine the reliability factors by providing a cloud storage menuto a user and receiving a selection for the cloud storage accessreliability indication 339 and a selection for the cloud storage datareliability indication 341.

The DS processing unit 16 dispersed storage error encodes the data file38 to produce encoded data slices 343 (e.g., a set of encoded dataslices for each data segment of the data file 38) in accordance with thereliability factors. The DSN memory 22 stores the encoded data slices343 in accordance with the reliability factors. The DS processing unit16 then sends an indication of the dispersed storage error encodingparameters 345 to the user device 13.

FIG. 17B is a diagram of a cloud storage menu 347 that includespotential selection continuums for a cloud storage access reliability349 and a cloud storage reliability 351. For example, endpoints of theselection continuum for the cloud storage access reliability 349 enablea selection for the cloud storage access reliability indication 353ranging between 1 nine of reliability and 30 nines reliability. Forinstance, a user selects 10 nines as the selection for the cloud storageaccess reliability invitation 353. As another example, endpoints of theselection continuum for the cloud storage reliability 351 enable aselection for the cloud storage data reliability indication 355 rangingbetween 1 nine of reliability and 30 nines reliability. For instance,the user selects 18 nines as the selection for the cloud storagereliability invitation 355.

FIG. 18 is a flowchart illustrating an example of generating a storedata object request. A method begins at step 338 where a processingmodule determines that a data storage request is a cloud data storagerequest. Such a determination may be based on one or more of a receiveddata object, a data type indicator, a request, a command, a message, alist, a predetermination, and an application output. For example, theprocessing module determines that the data storage request is the clouddata storage request when the data type indicator associated with thereceived data object indicates video evidence and a storage listrecommends storing video evidence in a cloud storage system.

The method continues at step 340 where the processing module determinesdata object metadata. Such data object metadata may include one or moreof a data type, a data size, a hash of the data object, a useridentifier (ID), a reliability indicator, an availability indicator, asecurity indicator, a performance indicator, and an estimated accessfrequency indicator. Such a determination may be based on one or more ofa data object, a request, a command, a message, a list, apredetermination, an application output, and a data object analysis. Forexample, the processing module determines the data object metadata toinclude a reliability indicator that indicates a higher level ofrequired reliability when the data object includes important financialrecords based on a data object analysis. The method continues at step342 where the processing module determines storage requirements based onone or more of the data object metadata, a data object, a request, acommand, a message, a list, a predetermination, an application output,and a data object analysis. For example, the processing moduledetermines storage requirements to include high storage reliability whenthe data object metadata includes a high reliability indicator.

The method continues at step 344 where the processing module determinesat least one of a cloud storage access reliability indication and acloud storage data reliability indication for the data storage request(e.g., reliability factors). Such a determination may include providinga cloud storage menu upon receiving the data storage request andreceiving at least one of a selection for the cloud storage accessreliability indication and a selection for the cloud storage datareliability indication. For example, the processing module provides thecloud storage menu and receives a 10 nines selection for the cloudstorage access reliability indication and a 18 nines for the cloudstorage data reliability indication.

Alternatively, determining one or both of the reliability factors mayinclude determining a data type of the data in the data storage request,which may further be done by accessing a register to obtain a user datatype setting and/or a system data type setting for one or both of thereliability factors. As another alternative, one or both of thereliability factors may be determined based on an application type thatgenerated data of the data storage request, which may further be done byaccessing a register to obtain a user application type setting and/or asystem application type setting for one or both of the reliabilityfactors. As yet another example, one or both of the reliability factorsmay be determined by accessing a register to obtain a default systemsetting and/or a user-defined default setting for one or both of thereliability factors.

The method continues at step 346 for the processing module sends thedata storage request and the cloud storage access reliability indicationand/or the cloud storage data reliability indication to a cloud storagesystem. The method continues at step 350 where the processing modulereceives an indication of dispersed storage error encoding parametersfrom the cloud storage system in response to the data storage request.For example, the indication of dispersed storage error encodingparameters includes a pillar width of 8 and a decode threshold of 5 eventhough even though an ideal match of the cloud storage accessreliability indication and the cloud storage data reliability indicationincludes a pillar width of 10 and a decode threshold of 6.Alternatively, or in addition to, the processing module may determinewhether the indication of dispersed storage error encoding parameterscompares favorably to the cloud storage access reliability indicationand the cloud storage data reliability indication. The processing moduleresends a new data storage request including at least one of a differentcloud storage access reliability indication and a different cloudstorage data reliability indication when the processing moduledetermines that the comparison is unfavorable.

FIG. 19 is a flowchart illustrating an example of generating a storedata object response. A method begins at step 352 where a processingmodule receives a data storage request and at least one of a cloudstorage access reliability indication and a cloud storage datareliability indication. Alternatively, or in addition to, the processingmodule may receive one or more of a data object, requested storageparameters, a user identifier (ID), a command (e.g., store, read,modify, delete, list, etc.), a priority indicator, a security indicator,and a performance indicator.

The method continues at step 354 where the processing module interpretsthe cloud storage access reliability indication and/or the cloud storagedata reliability indication to determine at least one of a storageaccess level and a storage reliability level. The method continues atstep 356 where the processing module determines candidate storageresource status where the status indicates one or more of memorycapacity, a memory utilization, available memory, access latency,availability, cost, performance history, and security history. Such adetermination may be based on one or more of a user ID, a vault lookup,a query, a list, a command, a message, a predetermination, and a historyrecord.

The method continues at step 358 where the processing module determinesdispersed storage error encoding parameters based on the at least one ofthe storage access level and the storage reliability level. Such adetermination includes at least one of determining a pillar width and aspacing between a decode threshold and a read threshold based on thestorage access level, wherein the pillar width and the spacing betweenthe decode threshold and the read threshold are proportional to thestorage access level, determining a spacing between the decode thresholdand the pillar width based on the storage reliability level, wherein thespacing between the decode threshold and the pillar width isproportional to the storage reliability level, determining a spacingbetween a write threshold and the pillar width based on the storageaccess level, wherein the spacing between the write threshold and thepillar width are proportional to the storage access level, anddetermining a spacing between the decode threshold and the writethreshold based on the storage reliability level, wherein the spacingbetween the decode threshold and write threshold is proportional to thestorage reliability level. For example, the processing module determinesthe dispersed storage error encoding parameters to include a readthreshold of 13 and a decode threshold of 10 when the storage accesslevel is 10 nines. As another example, the processing module determinesthe dispersed storage error encoding parameters to include a pillarwidth of 16 and a decode threshold of 10 when the storage reliabilitylevel includes 18 nines.

The method continues at step 360 where the processing module sends anindication of the dispersed storage error encoding parameters to arequesting device associated with the data storage request. Such anindication of the dispersed storage error coding parameters may includeone or more of a direct indication of the dispersed storage error codingparameters (e.g., a pillar width, a right threshold, a read threshold, adecode threshold, etc.) and an indirect indication of the dispersedstorage error coding parameters (e.g., an equivalent redundant array ofindependent disks (RAID) level, an equivalent replication level). Themethod continues at step 362 where the processing module encodes data ofthe data storage request based on the dispersed storage error encodingparameters to produce one or more sets of encoded data slices.Alternatively, or in addition to, the processing module sends the one ormore sets of encoded data slices to at least some candidate storageresources of a dispersed storage network (DSN) memory.

As may be used herein, the terms “substantially” and “approximately”provides an industry-accepted tolerance for its corresponding termand/or relativity between items. Such an industry-accepted toleranceranges from less than one percent to fifty percent and corresponds to,but is not limited to, component values, integrated circuit processvariations, temperature variations, rise and fall times, and/or thermalnoise. Such relativity between items ranges from a difference of a fewpercent to magnitude differences. As may also be used herein, theterm(s) “operably coupled to”, “coupled to”, and/or “coupling” includesdirect coupling between items and/or indirect coupling between items viaan intervening item (e.g., an item includes, but is not limited to, acomponent, an element, a circuit, and/or a module) where, for indirectcoupling, the intervening item does not modify the information of asignal but may adjust its current level, voltage level, and/or powerlevel. As may further be used herein, inferred coupling (i.e., where oneelement is coupled to another element by inference) includes direct andindirect coupling between two items in the same manner as “coupled to”.As may even further be used herein, the term “operable to” or “operablycoupled to” indicates that an item includes one or more of powerconnections, input(s), output(s), etc., to perform, when activated, oneor more its corresponding functions and may further include inferredcoupling to one or more other items. As may still further be usedherein, the term “associated with”, includes direct and/or indirectcoupling of separate items and/or one item being embedded within anotheritem. As may be used herein, the term “compares favorably”, indicatesthat a comparison between two or more items, signals, etc., provides adesired relationship. For example, when the desired relationship is thatsignal 1 has a greater magnitude than signal 2, a favorable comparisonmay be achieved when the magnitude of signal 1 is greater than that ofsignal 2 or when the magnitude of signal 2 is less than that of signal1.

While the transistors in the above described figure(s) is/are shown asfield effect transistors (FETs), as one of ordinary skill in the artwill appreciate, the transistors may be implemented using any type oftransistor structure including, but not limited to, bipolar, metal oxidesemiconductor field effect transistors (MOSFET), N-well transistors,P-well transistors, enhancement mode, depletion mode, and zero voltagethreshold (VT) transistors.

The present invention has also been described above with the aid ofmethod steps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claimed invention.

The present invention has been described, at least in part, in terms ofone or more embodiments. An embodiment of the present invention is usedherein to illustrate the present invention, an aspect thereof, a featurethereof, a concept thereof, and/or an example thereof. A physicalembodiment of an apparatus, an article of manufacture, a machine, and/orof a process that embodies the present invention may include one or moreof the aspects, features, concepts, examples, etc. described withreference to one or more of the embodiments discussed herein.

The present invention has been described above with the aid offunctional building blocks illustrating the performance of certainsignificant functions. The boundaries of these functional buildingblocks have been arbitrarily defined for convenience of description.Alternate boundaries could be defined as long as the certain significantfunctions are appropriately performed. Similarly, flow diagram blocksmay also have been arbitrarily defined herein to illustrate certainsignificant functionality. To the extent used, the flow diagram blockboundaries and sequence could have been defined otherwise and stillperform the certain significant functionality. Such alternatedefinitions of both functional building blocks and flow diagram blocksand sequences are thus within the scope and spirit of the claimedinvention. One of average skill in the art will also recognize that thefunctional building blocks, and other illustrative blocks, modules andcomponents herein, can be implemented as illustrated or by discretecomponents, application specific integrated circuits, processorsexecuting appropriate software and the like or any combination thereof.

What is claimed is:
 1. A computer readable memory device comprises: afirst memory section storing operational instructions that, whenexecuted by a computing device, causes the computing device to: receivea file access request; a second memory section storing operationalinstructions that, when executed by the computing device, causes thecomputing device to: identify a directory file path based on the fileaccess request; a third memory section storing operational instructionsthat, when executed by the computing device, causes the computing deviceto: determine that a directory address of a directory file of thedirectory file path is not available; and when the directory address isnot available, determine whether to reconstruct the directory address orto use a redundant directory file path; and a fourth memory sectionstoring operational instructions that, when executed by the computingdevice, causes the computing device to: when reconstructing thedirectory address: retrieve encoded components of the directory addressfrom a plurality of agent modules; and when at least a threshold numberof the encoded components of the directory address have been received,reconstruct the directory address from the at least a threshold numberof the encoded components of the directory address.
 2. The computerreadable memory device of claim 1, wherein the third memory sectionfurther stores operational instructions that, when executed by thecomputing device, causes the computing device to: when using theredundant directory file path, determine one or more directory addressesfor one or more redundant directory files in the redundant directoryfile path; and access a file via the one or more directory addresses ofthe redundant directory file path.
 3. The computer readable memorydevice of claim 1, wherein the directory address comprises: a dispersedstorage network (DSN) directory address.
 4. The computer readable memorydevice of claim 1, wherein the directory file comprises at least one of:a root directory file; an intermediate directory file; and a file-leveldirectory file.
 5. The computer readable memory device of claim 1,wherein the second memory section further stores operationalinstructions that, when executed by the computing device, causes thecomputing device to identify the directory file path when the fileaccess request is a write data request by: determining whether thedirectory file path exists; when the directory file path does not exist,creating the directory file path; determining whether to create aredundant directory file path; and when it is determined to create theredundant directory file path, creating the redundant directory filepath.